U.S. patent number 5,851,182 [Application Number 08/712,623] was granted by the patent office on 1998-12-22 for megavoltage radiation therapy machine combined to diagnostic imaging devices for cost efficient conventional and 3d conformal radiation therapy with on-line isodose port and diagnostic radiology.
Invention is credited to Velayudhan Sahadevan.
United States Patent |
5,851,182 |
Sahadevan |
December 22, 1998 |
Megavoltage radiation therapy machine combined to diagnostic
imaging devices for cost efficient conventional and 3D conformal
radiation therapy with on-line Isodose port and diagnostic
radiology
Abstract
A patient setup and treatment verification system for radiation
therapy having diagnostic imaging devices connected to a room
containing a megavoltage radiation therapy machine. The diagnostic
rooms and the megavoltage therapy room are connected to each other
by openings in the shared secondary wall of the accelerator or
through an anteroom to the megavoltage therapy room. Daily patient
setup for routine and three-dimensional conformal radiation therapy
and on-line treatment port verification with superimposed isodose
are done with the patient on a diagnostic-imaging table. The
patients are transferred from the diagnostic table to the treatment
table without changing the verified treatment position. Sliding or
rotating shield or maze walled anteroom are used for radiation
protection. A patient setup with multiple diagnostic devices in
separate chambers allows rapid turnover of patients in the
megavoltage treatment room with patients spending much less time in
the treatment room. When the diagnostic device is not in use with
the megavoltage therapy machine for radiation therapy of patients
in a radiation oncology department, it can be used as a routine
diagnostic device for a diagnostic radiology department.
Inventors: |
Sahadevan; Velayudhan (Beckley,
WV) |
Family
ID: |
24862903 |
Appl.
No.: |
08/712,623 |
Filed: |
September 11, 1996 |
Current U.S.
Class: |
600/407; 378/63;
378/65 |
Current CPC
Class: |
A61N
5/1049 (20130101); A61N 2005/1063 (20130101); A61N
2005/1094 (20130101) |
Current International
Class: |
A61N
5/10 (20060101); A61B 005/05 () |
Field of
Search: |
;128/653.1,653.2
;364/413.13 ;378/62,63,64,65 ;600/407,410 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Khan, F.M.; The Physics of Radiation Therapy, Second Edition,
Megavoltage Therapy, pp. 49-66, 1994. .
World Health Organization Conference, Advisory Group Consultation
on the Design Requirements for Megavoltage X-ray Machine for Cancer
Treatment in Developing Countries, Dec. 1993, publication pending.
.
Quotation: Varian Oncology Systems, CLINAC 600C Radiotherapy Linear
Accelerator, 1993. .
Quotation: Philips Medical Systems SL15 Linear Accelerator, 1993.
.
Quotation: Siemens Oncology Care Systems, Mevatron 6740, 1993.
.
Quotation: Theratronics, Theratron 1000 Cobalt Unit and
accessories, 1993. .
Khan, F.M.; Treatment Planning II: Patient Data, Corrections, and
Setup, The Physics of Radiation Therapy, Second Edition, pp.
260-314, 1994. .
Quotation: Varian Oncology Systems, Ximatron CX. 3 phase 12 inch
fluroscopy and Ximatron/CT Opinion, 1993. .
Ragan, D.P., et al; Clinical Results of Computerized
Tomography-Based Simulation With Laser Marking, Int. J. Radiation
Oncology Biol. Phys., vol. 34; pp. 691-695, 1996. .
Siemens, TMS Advanced Planning System for Radiation Oncology, 1996.
.
Siemens, Virtual Simulation System and Conformal Field Projector
for Radiation Oncology, 1996. .
GE Advantage SIM, CT Simulation in 3D, GE Medical Systems, 1996.
.
Kooy, H. M., et al, Treatment Planning for Stereotactic
Radiosurgery of Intracranial Lesions, Int. J. Radiation Oncology
Biol. Phys., 21: pp. 683-693, 1991. .
Tsujii, Hirohiko, et al, The Value of Treatment Planning Using CT
and An Immobilizing Shell In Radiotherapy For Paranasal Sinus
Carcinomas, Int. J. Radiation Oncology Biol. Phys., 16: pp.
243-249, 1989. .
Sibley, G. S., et al., The Treatment of Stage III Nonsmall Cell
Lung Cancer Using High Dose Conformal Radiotherapy, Int. J.
Radiation Oncology Biol. Phys., 33: pp. 1001-1007, 1995. .
Vijayakumar, S., et al, Implementation of Three Dimensional
Conformal Radiation Therapy: Prospects, Opportunities, and
Challenges, Int. J. Radiation Oncology Biol. Phys., 33: pp.
979-983, 1995. .
Rosenman, J., et al, Three-Dimensional Display Techniques in
Radiation Therapy Treatment Planning, Int. J. Radiation Oncology
Biol. Phys., 16: pp. 263-269, 1989. .
Khan, F. M., Radiation Protection, The Physics of Radiation
Therapy, Second Edition, pp. 474-503, 1994. .
Shleien, B. (Ed), The Health Physics and Radiological Health
Handbook, Revised Edition, Exposure and Shielding From External
Radiation, pp. 163-218, 1992..
|
Primary Examiner: Lateef; Marvin M.
Assistant Examiner: Mercader; Eleni Mantis
Attorney, Agent or Firm: Steptoe & Johnson
Claims
What is claimed is:
1. An improved patient handling system for use with a radiation
therapy device and medical imaging device, comprising:
a first chamber having a radiation therapy device; a second chamber
having a medical imaging device; and a first wall dividing said
first chamber and said second chamber and having means defining a
hole in said first wall for providing communication between said
first chamber and said second chamber;
said first wall further having radiation shielding means including
an open position allowing communication between said first and
second chambers and a closed position for selectively covering said
first wall hole defining means to seal said second chamber from
radiation from the radiation therapy device in said first
chamber;
a cradle located on the medical imaging device for receiving a
table top insert and having means defining a groove on said
cradle;
a cradle located on the radiation therapy device for receiving said
table top insert and having means defining a groove on said
cradle;
said table top insert having a patient securing means for securing
a patient in a fixed position on said table top insert and having a
lower surface for securing rollers to said lower surface and
wherein said rollers are sized to fit within said groove of the
medical imaging device and said groove of the radiation therapy
device;
said means defining said hole in said first wall being sized and
positioned such that said table can be rolled on said rollers from
said medical imaging device cradle to said radiation therapy device
cradle without changing the position of the patient.
2. An improved patient handling system according to claim 1 further
wherein
said radiation shielding means includes a sliding shield door
having a hollow core for receiving a liquid shielding material;
said radiation shielding means further including an upper reserve
tank in said wall for receiving said liquid shielding material, a
lower reserve tank in said wall for receiving said liquid shielding
material, at least one pump for pumping said liquid shielding
material from said lower reserve tank to said upper reserve tank, a
valve in said sliding shield door for selectively allowing said
liquid shield material to flow from said upper reserve tank to said
hollow core, and an outlet valve for selectively allowing said
liquid shield material to flow from said hollow core to said lower
reserve tank.
3. An improved patient handling system according to claim 2 further
wherein said radiation shielding means includes lead, concrete, and
liquid metals.
4. An improved patient handling system according to claim 2 wherein
said radiation shielding means includes a plurality of doors each
having rollers; and said first wall includes a concrete portion for
slidingly receiving said rollers on said plurality of door rollers
and driving means for driving said plurality of door rollers for
sliding said plurality of radiation shielding doors.
5. An improved patient handling system according to claim 4 wherein
said driving means includes a motor.
6. An improved patient handling system according to claim 4 wherein
said plurality of radiation shielding doors have means defining a
hollow core therein for receiving a liquid shielding material.
7. An improved patient handling system according to claim 6 wherein
said liquid shielding material is a metal.
8. An improved patient handling system according to claim 6 further
wherein said liquid metal is a Lipowitz metal.
9. An improved patient handling system according to claim 8 wherein
said Lipowitz metal is substantially 70 degrees Celsius.
10. An improved patient handling system according to claim 1
further comprising:
a third chamber having a second medical imaging device and a second
wall dividing said first chamber and said third chamber and having
a second means defining a second hole in said second wall for
providing communication between said first chamber and said third
chamber;
a cradle located on the second medical imaging device for receiving
a table top insert and having means defining a groove on the second
medical imaging device cradle for receiving the table top insert
rollers;
said second means defining said second hole in said second wall
being sized and positioned such that said table can be rolled on
said rollers from said second medical imaging device cradle to said
radiation therapy device cradle without changing the position of
the patient.
11. An improved patient handling system according to claim 10,
wherein the medical imaging device includes a gantry having means
defining an opening for receiving the patient and said table top
insert on said medical imaging cradle in said opening; said gantry
further includes an entrance and an exit; and wherein
said first wall is intermediate said medical imaging device gantry
exit and the radiation therapy device.
12. An improved patient handling system according to claim 10
further wherein the radiation therapy device is selected from a
Computed Tomography device, Magnetic Resonance Imaging device or a
simulator combined with a Computed Tomography device.
13. An improved patient handling system according to claim 10
further wherein the radiation therapy device is selected from
either a medical linear accelerator, a cobalt-60 machine, or a
medical microtron.
14. The improved patient handling system according to claim 1,
further comprising:
an antechamber adjacent to said first chamber via a door
opening;
a means for communicating between said antechamber and said first
chamber, wherein said means for communicating reduces shielding
requirements between said first chamber and said antechamber;
and
a plurality of second chambers adjacent to said antechamber such
that said first chamber communicates with said plurality of second
chambers via said antechamber and said means for communicating;
whereby a patient is transported on said table top insert from one
said second chamber to said first chamber on top of an extension
table via said antechamber with minimal change in position of the
patient on said table top insert.
15. The improved patient handling system according to claim 14,
wherein said means for communicating between said antechamber and
said first chamber is a plurality of walls in said first chamber
creating a maze configuration, thereby reducing scattered radiation
reaching said maze configuration.
16. The improved patient handling system according to claim 15,
wherein said plurality of walls comprises:
a short maze wall; and
a long maze wall having a hole opening for a patient's transport,
said hole opening aligned with said door opening.
17. The improved patient handling system according to claim 14,
further comprising
an operating room;
a means for connecting said operating room to one said second
chamber; and
a means for connecting said operating room to said antechamber.
18. The improved patient handling system according to claim 17,
wherein said antechamber reduces scattered radiation from the
radiation therapy device in said first chamber that reaches said
operating room and said second chambers.
19. The improved patient handling system according to claim 17,
wherein said means for communicating between said antechamber and
said first chamber is a plurality of walls in said first chamber
creating a maze configuration, thereby reducing scattered radiation
from the radiation therapy device in said first chamber that
reaches said antechamber, said second chambers and said operating
room.
20. The improved patient handling system according to claim 14,
further comprising a method of transferring a patient secured to a
table top insert on said cradle of the medical imaging device from
one said second chamber to said first chamber via said antechamber,
wherein said method of transferring the patient comprises the steps
of:
a. advancing said table top insert on said rollers of said table
top insert within said grooves of the medical imaging device such
that said table top insert extends over the medical imaging
device's back exit and into said cradle of said extension
table;
b. advancing completely said table top insert onto said extension
table;
c. advancing said extension table from said second chamber to said
antechamber through a door opening;
d. advancing said extension table from said antechamber to said
first chamber through said door opening;
e. advancing said table top insert on said rollers of said table
top insert within said grooves of said extension table such that
said table top insert extends over an end of said extension table
and into said cradle of the radiation therapy device; and
f. advancing completely said table top insert onto the radiation
therapy device such that a treatment site of the patient is under
the radiation therapy device's treatment head.
21. The improved patient handling system according to claim 14,
further comprising:
one or more rails on the floor connecting the radiation therapy
device in said first chamber, said antechamber, and the medical
imaging devices in said second chambers; and
an extension table with a cradle having means defining a plurality
of grooves on said extension table wherein said grooves of said
extension table are sized to receive said rollers of said table top
insert, thereby engaging and guiding said table top insert, and
having a means for traveling along said rails;
wherein the patient is transferred between said first chamber, said
antechamber, and said second chambers on said table top insert on
said extension table by traveling along said rails.
22. The improved patient handling system according to claim 1,
further comprising an extension table having means defining a
plurality of grooves on said extension table wherein said grooves
of said extension table are sized to receive said rollers of said
table top insert, thereby engaging and guiding said table top
insert.
23. The improved patient handling system according to claim 22,
wherein said cradle of the radiation therapy device, said cradle of
the medical imagery device, and said cradle of said extension table
further comprise:
a means for latching together the radiation therapy device, the
medical imaging device and said extension table;
a male notch; and
a female notch;
whereby said male notch and said female notch are aligned when a
radiation therapy device, medical imagery device or an extension
table are latched together, thereby facilitating the transport of a
patient on said table top insert.
24. The improved patient handling system according to claim 22,
further comprising a method of transferring a patient secured to a
table top insert on said cradle of the medical imaging device from
said second chamber to said first chamber through a door opening in
said first wall, wherein said method of transferring the patient
comprises the steps of:
a. advancing said table top insert on said rollers of said table
top insert within said grooves of the medical imaging device such
that said table top insert extends over an end of the medical
imaging device and onto said extension table;
b. advancing completely said table top insert onto said extension
table;
c. advancing said extension table from said second chamber to said
first chamber through the door opening;
d. advancing said table top insert on said rollers of said table
top insert within said grooves of said extension table such that
said table top insert extends over an end of said extension table
and into said cradle of a table of the radiation therapy device;
and
e. advancing completely said table top insert onto the table of the
radiation therapy device such that a treatment site of the patient
is under the radiation therapy device's treatment head.
25. The improved patient handling system according to claim 14,
further comprising:
a third chamber having a second radiation therapy device; and
a means for communicating between said third chamber and said
antechamber, wherein said means for communicating reduces shielding
requirements between said third chamber and said antechamber.
26. The improved patient handling system according to claim 25,
wherein said second radiation therapy device has a special
collimator for three dimensional conformal radiation therapy or for
radiosurgeries.
27. The improved patient handling system according to claim 1,
further comprising:
a third chamber having a second radiation therapy device equipped
with a special purpose collimator for three dimensional conformal
radiation therapy or for radiosurgeries;
a second wall dividing said third chamber and said second chamber
and having a means defining a hole in said second wall for
providing communication between said third chamber and said second
chamber; and
said second wall further having radiation shielding means including
an open position allowing communication between said third chamber
and said second chamber and a closed position for selectively
covering said hole in said second wall defining means to seal said
second chamber from radiation from the second radiation therapy
device in said third chamber;
wherein, in said second chamber, said medical imagery device's back
exit faces said third chamber.
28. The improved patient handling system according to claim 1,
wherein said first chamber is hexagonal in shape and said radiation
therapy device is placed away from its primary beam's direction to
take advantage of the distance traveled by scattered radiation;
and
a plurality of second chambers adjacent to said first chamber
wherein each said second chamber has a first wall dividing said
first chamber and said second chamber and a means defining a hole
in said first wall and a radiation shielding means.
29. The improved patient handling system according to claim 14,
wherein said first chamber, a heavily shielded room, and said
plurality of second chambers are placed in a hexagonal arrangement,
wherein said antechamber provides a barrier between said first
chamber and said plurality of second chambers, such that a patient
is transported from one said second chamber to said first chamber
with a minimal change in position on said table top insert.
30. The improved patient handling system according to claim 1,
further comprising:
a third chamber having a medical imaging device and a second wall
dividing said first chamber and said third chamber and having means
defining a hole in said second wall for providing communication
between said first chamber and said third chamber, wherein the
medical imaging device in said third chamber is placed at ninety
degrees to the radiation therapy device in said first chamber such
that the medical imaging device's front end faces the radiation
therapy device, thereby allowing the placement of a treatment site
of the patient under the radiation therapy device's treatment head
with rotation of the patient; and
a fourth chamber having a medical imaging device and a third wall
dividing said first chamber and said fourth chamber and having
means defining a hole in said third wall for providing
communication between said first chamber and said fourth chamber,
wherein the medical imaging device in said fourth chamber is placed
at two hundred seventy degrees to the radiation therapy device in
said first chamber such that the medical imaging device's front end
faces the radiation therapy device, thereby allowing placement of a
treatment site of the patient under the radiation therapy device's
treatment head with rotation of the patient;
wherein the radiation therapy device is placed in said first
chamber such that the radiation therapy device faces the back exit
of the medical imaging device in said second chamber, thereby
allowing placement of a treatment site of the patient under the
radiation therapy device's treatment head without rotation of the
patient.
31. The improved patient handling system according to claim 1,
further comprising a method of transferring a patient secured to a
table top insert in said cradle of the medical imaging device from
said second chamber to said first chamber through said hole in said
first wall, wherein said method of transferring the patient
comprises the steps of:
a. advancing said table top insert on said rollers of said table
top insert within said grooves of the medical imaging device such
that said table top insert extends over an end of the medical
imaging device and into said hole in said first wall;
b. advancing said table top insert on said rollers of said table
top insert through said hole in said first wall and into said
cradle of the radiation therapy device such that said table top
insert extends through said hole and onto an end of the radiation
therapy device;
c. advancing completely said table top insert onto a table of the
radiation therapy device; and
d. rotating the table of the radiation therapy device to bring a
treatment site of the patient under the radiation therapy device's
treatment head.
32. The improved patient handling system according to claim 1,
further comprising a method of treating a patient secured to a
table top insert without positional errors when transferring the
patient from a medical imaging device in said second chamber to a
radiation therapy device in said first chamber, wherein said method
of treating the patient comprises the steps of:
a. placing the patient in a treatment position on said table top
insert, wherein said table top insert on which the patient is
secured is in said cradle of the medical imaging device in said
second chamber;
b. generating and marking one or more images of a treatment field
on the patient in said treatment position using the medical imaging
device;
c. transferring said table top insert from the medical imaging
device to the radiation therapy device in said first chamber
wherein the patient remains in said treatment position; and
d. treating the patient in said treatment position with the
radiation therapy device.
33. The improved patient handling system according to claim 1,
further comprising a method of treating a patient secured to a
table top insert without positional errors when transferring the
patient from a medical imaging device in said second chamber to a
radiation therapy device in said first chamber, wherein said method
of treating the patient comprises the steps of:
a. placing the patient in a treatment position on said table top
insert, wherein said table top insert on which the patient is
secured is in said cradle of the medical imaging device in said
second chamber;
b. generating one or more images of a treatment field and marking
said treatment field on the patient in said treatment position with
the medical imaging device and a marker and generating one or more
radiation isodose representations on said images with a treatment
planning computer, wherein said images are on-line treatment
portals with superimposed computer generated isodose to the true
three dimensional visualized treatment region for radiation
therapy.
c. transferring said table top insert from the medical imaging
device to the radiation therapy device in said first chamber
wherein the patient remains in said treatment position; and
d. treating the patient in said treatment position with the
radiation therapy device by using conventional and three
dimensional conformal radiation therapy, stereotactic radiosurgery
and intraoperative radiation therapy.
34. The improved patient handling system according to claim 1,
further comprising a method of treating a patient secured to a
table top insert without positional errors when transferring the
patient from a medical imaging device in said second chamber to a
radiation therapy device in said first chamber, wherein said method
of treating the patient comprises the steps of:
a. placing the patient in a treatment position on said table top
insert, wherein said table top insert on which the patient is
secured is in said cradle of the medical imaging device in said
second chamber;
b. generating one or more images of a treatment field and its
surrounding normal tissue and critical structures in the patient in
said treatment position and marking said treatment field on the
patient's skin while the patient is in the treatment position with
the medical imaging device and generating a radiation isodose with
a treatment planning computer, resulting in said images being
isodose superimposed port verification images;
c. transferring said table top insert from the medical imaging
device to the radiation therapy device in said first chamber
wherein the patient remains in said treatment position; and
d. treating the patient in said treatment position with the
radiation therapy device, thereby maximizing a dose of radiation
directed to a tumor in said treatment field and minimizing the dose
of radiation directed to the normal tissue and critical structures
surrounding the tumor.
35. The improved patient handling system according to claim 34,
wherein generating said images with said treatment planning
computer results in online medical imaging and improves quality
radiation therapy and quality control.
36. The improved patient handling system according to claim 34,
wherein generating said images with said treatment planning
computer, resulting in online medical imaging, and using said port
verification images improves quality radiation therapy and quality
control.
37. The improved patient handling system according to claim 1,
further comprising a method of treating a patient secured to a
table top insert such that there are minimal positional errors when
transferring the patient from a medical imaging device in said
second chamber to a radiation therapy device in said first chamber,
wherein said method of treating the patient comprises the steps
of:
a. placing the patient in a treatment position on said table top
insert, wherein said table top insert on which the patient is
secured is in said cradle of the medical imaging device in said
second chamber;
b. generating an image of a treatment site on the patient in said
treatment position with the medical imaging device, wherein the
medical imaging device is equipped with markers resulting in an
image treatment field being marked on the patient's skin and said
image is superimposed with radiation isodose distribution to said
treatment site and its surrounding normal tissue including the
critical structures;
c. transferring said table top insert from the medical imaging
device to the radiation therapy device in said first chamber
wherein the patient remains in said treatment position; and
d. treating the patient in said treatment position with the
radiation therapy device, thereby maximizing a dose of radiation
directed to a tumor in said treatment field and minimizing the dose
of radiation directed to the normal tissue and critical structures
surrounding the treatment site.
38. The improved patient handling system according to claim 1,
wherein the medical imaging device in said second chamber is used
independent of the radiation therapy device in said first chamber
such that the medical imaging device is used for routine diagnostic
imaging purposes.
39. The improved patient handling system according to claim 1,
wherein the radiation therapy device provides advanced radiation
therapy such as three dimensional radiation therapy, radiosurgery,
intraoperative radiation therapy and three dimensional display of
brachytherapy implant source.
40. The improved patient handling system according to claim 1,
wherein said radiation shielding means is a rotating cylindrical
shielding door having a central opening, a hollow core filled with
a radiation blocking material, and a means for rotating.
41. The improved patient handling system according to claim 40,
wherein said means for rotating is a motor driven chain.
42. The improved patient handling system according to claim 40,
wherein said means for rotating is a mechanical handle.
43. The improved patient handling system according to claim 40,
wherein said radiation blocking material is lead.
Description
The present day radiation therapy for cancer is delivered mostly by
megavoltage machines like the medical accelerators or by cobalt-60
units. Among the medical accelerators, linear accelerators are the
most widely used system. A few other medical accelerator systems
are also in use. They include the old Van de Graaff generator, the
betatron and the microtron. Both the Van de Graaff and the betatron
accelerators are technically inferior to cobalt-60 unit and to the
widely used linear accelerators (Kahn, F. M., Clinical radiation
generators, in The Physics of Radiation Therapy, 2.sup.nd ed.,
49-66,1994).
The cobalt-60 units are relatively cheaper to purchase and to
maintain than the medical accelerators. Therefore, cobalt-60
machines are the most widely used treatment machines in countries
where the purchase and maintenance costs are of major concern. The
lower maintenance cost of the cobalt-60 unit is compensated by the
five-year periodic replacement of the cobalt-60 source that is very
costly. The other major disadvantages of the cobalt-60 machines
include its low energy (1.33 MV), high penumbra, higher skin dose,
lower dose rate and the difficulties associated with the source
handling. If the source is not replaced by the scheduled time, it
can result in very poor treatment. The partially decayed cobalt-60
source is an environmental hazard of greater magnitude. The cost of
the environmental cleaning up of a partially decayed and mishandled
cobalt-60 source was over 34 million dollars in a single incident.
There were many radiation associated tragic deaths including those
innocent: children who use to play at the dumping site of the
cobalt-60 source. For these reasons, the World Health Organization
is attempting to replace the present cobalt-60 units with more
efficient medical accelerators (World Health Organization, Advisory
Group Consultation on the Design for Megavoltage x-ray Machines for
Cancer publication pending).
The much higher cost of the medical accelerators both for its
initial purchase and its subsequent maintenance is a greater
hindrance in its widespread use especially in those countries with
limited resources. A today's standard 6 MV medical linear
accelerator with its accessory systems could cost about $700,000 or
more (Quotation: Varian Oncology Systems 1993, Philips Medical
Systems 1993, Siemens Medical Systems 1993). The cost of an
accelerator with 15-20 MV photons and varying energy electrons or a
modern medical racetrack microtron could reach several millions. A
modern cobalt-60 unit with higher source strength may cost to about
$ 250,000 but when the accessories, the table and the cost of the
source are all added together, its cost is about over $400,000
(Quotation: Theratronics 1993).
The computed tomography (CT) of the tumor bearing regions obtained
with the aid of a diagnostic CT is generally used for treatment
planning and dosimetric calculations. (Khan, F. M., Treatment
planning II: Data, Corrections, and Setup; in The Physics of
Radiation Therapy, 2.sup.nd ed., 260-314,1994). Since these CT are
taken in a different department with a routine diagnostic CT, they
are often not reproducible under the treatment conditions of a
patient on the radiation therapy machine. This positioning error
can cause significant error in radiation dose given to the tumor
and to the surrounding normal tissue. In general, fractionated
radiation therapy is given as one treatment a day for about 30 to
35 treatments to a patient. The difficulties associated with the
day to day identical treatment positioning of a patient on the
treatment table as the initial dosimetric planning made with the
aid of the initial simulation and the diagnostic CT taken elsewhere
increases the cumulative dosimetric error both to the normal and
the tumor tissue.
Varying methods for aligning the patient to the intended region of
treatment and surgery has been developed but in those methods the
patients are positioned on the diagnostic imaging table for the
initial planning and days after the planning is completed, attempts
are made to reposition the patient on the radiation therapy
machine's table in an identical manner as the patient was on the
diagnostic imaging table before (Miller, D. W.; Patient alignment
system and procedure for radiation treatment; U.S. Pat. No.
5,117,829., 1992; Miller, D. W., Method of assembly and whole body,
patient positioning and repositioning support for use in radiation
beam therapy systems; U.S. Pat. No. 4,905,267; Klausz, R., Method
of controlling the positioning of a patient with respect to an
X-ray device and installation for carrying out such method; U.S.
Pat. No. 4,633,494). The days later reproducibility of patient's
positioning as was on the diagnostic imaging table before is
difficult and often can be inaccurate. During the course of several
weeks of treatment, the patient's contour can significantly change
causing the initial planning and the patient's fitting position in
an immobilizing device increasingly inaccurate. In this invention,
the patient's treatment setup is daily verified with the diagnostic
imaging device and the patient is transported in this verified
position from the diagnostic table to the treatment table of the
megavoltage treatment machine.
Simulators equipped with CT are available to increase the accuracy
of the treatment planning (Kahn, F. M., Treatment simulation; in
The Physics of Radiation Therapy, 2.sup.nd ed., 277,1994). The cost
of such a modern simulator will exceed the cost of a medium energy
medical linear accelerator. (Varian Ximatron/CT Option, quotation
by Varian Oncology Systems; received in 1993) Therefore, the CT
equipped simulators are not frequently used in most radiation
therapy departments. Another recent advancement in Radiation
Oncology is the introduction of the CT-based simulator. In this
system, a commercial CT is equipped with computer controlled laser
drawing device and creation of digital reconstructed radiographs
are used. The laser drawing is used to transfer the CT simulation
to the patient for the appropriate patient's skin markings. (Ragan
D. P., et. al., Clinical results of computerized tomography-based
simulation with laser patient marking; in Int. J. Radiation
Oncology Biol. Phys., 34: 691-695,1996; Advanced Planning System
for Radiation Oncology, advertisement by Siemens Medical Systems,
Inc., received in 1996; Virtual Simulation System and Conformal
Field Projector for Radiation Oncology, advertisement by Siemens
Medical Systems, Inc., received in 1996; GE Advantage SIM CT
Simulation in 3D, advertisement by GE Medical Systems, received in
1996). Again this is very costly. Moreover all these systems cannot
reproduce the daily treatment setup on the treatment table as in
the case of this invention.
In an effort to minimize the daily patient setup error, weekly port
verification films with the patient on the treatment table in
treatment position are taken with the high energy beams of the
treatment machines (Kahn, F. M., Treatment verification; in Physics
of Radiation Therapy, 2.sup.nd ed., 277-281,1994). Because of the
Compton effect of the megavoltage beam the image quality of the
port film is poorer than the conventional x-ray films. To make the
necessary adjustments, the port film has to be reviewed while the
patient is still on the accelerating table and in the treatment
position. The time needed to develop each port film taken keeps the
patient for longer time on the treatment table. It can be very
uncomfortable to the patient. It also reduces the efficient use of
the accelerator time. In the process of taking a port film, usually
a 0.004-0.007 cGy exposure is made to the intended treatment region
and on top of it a wider full field 0.002-0.004 cGy exposure is
also made. The second exposure is made to assist the anatomic
interpretation of the region of interest. This exposes a wider
anatomic region to the high-energy radiation than the intended
tumor bearing treatment area. It is not practical to take daily
treatment verification films. Therefore, a compromise is made by
making the treatment port verification only once a week. The
developing electronic portal imaging devices (Lam, W. C.; On-line
treatment monitoring for radiation therapy; U.S. Pat. No.
4,365,341,1982; Kahn, F. M., Electronic Portal Imaging, in The
Physics of Radiation Therapy, 2.sup.nd ed. 278-279,1994) are costly
and it also does not give the diagnostic x-ray quality images.
Three dimensional localization of the tumor and the critical normal
structures used in the CT aided 3D conformal radiation therapy
planning for stereotactic radiosurgery (Brunnett, K. J., Computer
assisted stereotactic surgery system and method; U.S. Pat. No.
4,791,934,1988; Kooy, H. M., et al., Treatment planning for
stereotactic radiosurgery of intra-cranial-leasions; in Int. J.
Radiation Oncology Biol. Phys., 21: 683-693,1991) and treatment of
the paranasal, (Hirohiko, T., et. al., The value of treatment
planning using CT and immobilizing shell in radiotherapy for
paranasal sinus carcinomas; in Int. J. Radiation Oncology Biol.
Phys. 16: 1989) chest Sibley, G. S., et al. The treatment of stage
III non-small cell lung cancer using high dose conformal
radiotherapy, in Int. J. Radiation Oncology Biol. Phys., 33:
1001-1007, 1995) and other tumor sites (Vijayakumar, S., et al.,
Implementation of three dimensional conformal radiation therapy:
prospects, opportunities, and challenges; in Int. J. Radiation
Oncology Biol. Phys., 33: 979-983,1995) can be improved by
pretreatment port verification with a CT and subsequent transport
of the patient from the CT table to the accelerator table without
changing the patient's positioning. It facilitates reproducible
treatment setup as is done with the CT. The rapid increase of the
three dimensional conventional radiation therapy (3DCRT) has
rendered improved control of tumor growth, long term survival and
reduced complication of radiation therapy. The present widely used
two-dimensional radiation therapy planning (2D) often
underestimates the gross tumor volume and hence the chances for
missing part of the tumor in the treatment field or its inadequate
dosage. The conventional transverse CT display format is not an
ideal display of the anatomic relation to the radiation beam as
usually used in a treatment settings. The path of the radiation
beam that is not in perpendicular to the axis of the transverse CT
slice is difficult to visualize. In the 2D planning the isodose is
displayed in multiple CT slices which also makes it difficult to
compare the best treatment plan. The conventional transverse CT
fails to confirm the continuity of a radioactive seed used in the
brachytherapy from one CT slice to the next one. The 3D volume
rendering as used in the 3DCRT overcomes these shortcomings of the
2D (Roseman, J. et. al., Three- dimensional display techniques in
radiation therapy treatment planning; in Int. J. Radiation Oncology
Biol. Phys., 16: 263-269,1989). However when the volume rendering
3DCRT is done with the patient on the CT table at a distant and
different setup Diagnostic Radiology Department than the actual
treatment delivered with the patient on the treatment table of a
Radiation Oncology Department, many of these advantageous of the
3DCRT are lost because of the difficulties associated with the
reproducibility of the patient's setups at one department to the
other.
The stereotactic radiosurgery of intracranial tumors and vascular
malformations needs precise and reproducible volume rendering 3DCRT
planning. At a Radiation Oncology Department where many
stereotactic radiosurgeries are done, the weekly number of such
procedures is limited to about four patients. The low number
results for having to wait for access to an accelerator, delay in
CT data transfer from the Radiology department to the Radiation
Oncology department for treatment planning and the subsequent
efforts to set up the patient on the accelerator table identically
as the CT images was obtained at the Radiology department's CT.
Excluding the waiting time for the access to the accelerator, the
present turn-around time for the stereotactic radiosurgery is about
four hours (Kooy, H. M., et. al., Treatment planning for
stereotactic radiosurgery of intra-cranial lesions; in Int. J.
Radiation Oncology Biol. Phys. 21: 683-693, 1991).
This invention overcomes the above difficulties. After the daily
on-line isodose superimposed treatment port verification by the
diagnostic imaging device, the patient is transported directly from
the diagnostic imaging device's table to the megavoltage radiation
therapy machine's table. From the CT table the flat table top with
the patient is rolled on to an extension table. The extension table
with the flat tabletop 15 inserted and the patient is rolled on
rails to the connecting accelerator room. The patient is
transferred to the accelerator table by rolling the flat tabletop
insert with the patient to the accelerator table. In this case,
after the setup and verification of a patient's treatment on the
diagnostic imaging table, the patient does not change the verified
setup for treatment. In contrast to this, the present practice is
to hope for identical positioning of the patient using markings
made on the skin during the simulation with the x-ray simulator.
With the present practice of CT imaging at the Diagnostic Radiology
Department and delivery of the radiation therapy at a distant
Department of Radiation Oncology, it is difficult to reproduce the
initial treatment setup at the Department of Radiation Oncology
with its megavoltage radiation therapy machine or by the simulator.
Moreover during the course of six weeks conventional radiotherapy,
there will be physical changes in a patient to make the initial
skin markings more and more inaccurate. The significance of this
invention's patient transport from the diagnostic-imaging table to
the treatment table directly with the daily on-line treatment port
verification to improve the quality of the treatment is
obvious.
Radiation therapy is the most cost effective treatment for cancer
in most developing countries. When diagnosis of cancer is made too
late, the surgical treatment is not successful. Chemotherapy is
very expensive and is often not well tolerated. By year 2015, about
9 million new cancer cases are expected per year in the developing
countries of the world. There are not many medical accelerators in
developing countries. (World Health Organization, Advisory Group
Consultation on the Design for Megavoltage x-ray Machines for
Cancer Treatment in Developing Countries, 6-10 December 1993,
Washington, D.C., publication pending). There is also a great
shortage of modern diagnostic devices in the developing countries.
This shortage will be even higher in the future if no innovative
developments are made. Presently, most patients are treated with
antiquated old cobalt-60 machines. This is associated with the
prohibitive cost of medical accelerators and the modern diagnostic
devices. The need to treat as many patients as possible every day
with any available megavoltage machine makes the quality and
precision of the treatment to suffer. Therefore, there is an acute
need for more cost effective and high quality medical accelerators,
diagnostic devices and its ancillary machines for delivery of
today's standard diagnostic radiology and radiation therapy in the
developing countries. This invention's efficient utilization of a
megavoltage machine to treat three to four times the number of
patients treated as now and the shared use of diagnostic imaging
devices for diagnostic radiology and radiation therapy brings the
cost-effective, most modern diagnosis and treatment facilities to
the developing countries as well.
The megavoltage radiation therapy machine described in this
invention can be any of the presently used megavoltage radiation
therapy machines including the accelerators or even a cobalt 60
machine. However the disadvantages of the cobalt 60 machine has
been described earlier. Among the accelerators, the medical linear
accelerators are the most commonly used ones at the present. In the
following descriptions, one should know that the word accelerator
is used as synonymous to any megavoltage radiation therapy
machines.
Any of the commonly used imaging devices can be used for patient
setup and verification. In the following examples, the CT combined
accelerator is used as an example, but the CT can be replaced with
any other appropriate diagnostic imaging devices. The diagnostic
imaging techniques using the magnetic resonance imaging (MRI),
ultrasonic tomograms, transverse tomographic x-rays or any other
similar imaging devises can also be used in place of the CT. The
advantages of the MRI and ultrasonic tomograms include no ionizing
radiation is used for imaging. In these cases, instead of the CT,
another imaging device is placed in the rooms adjacent to the
accelerator. There are both advantages and disadvantages for these
other imaging devices. The MRI allows a better imaging of soft
tissue but it cannot image bone or calcifications. Additional
difficulties associated with MRI are the magnetic interference with
the metallic objects and the smaller hole of the MRI scanner. Since
the megavoltage room and the MRI rooms in this invention are
separated from each other, the interference from the metallic
objects used in radiation therapy in the megavoltage room is
avoided. The drawings shown in the diagnostic room can either be a
CT or an MRI. The image quality of the ultrasonic tomogram is
poorer than that of the CT and the MRI, but it is much cheaper. It
also provides real time information that is extremely useful in the
rapid set up of patients for treatment. Because of its smaller size
and the real-time scan capability of the ultrasound, it can also be
used as an added device within the accelerator room itself for the
rapid treatment setup verification of a patient on the accelerator
table. The transverse tomogram have poor contrast and spatial
resolution. It can also produce artifacts that could interfere with
the dosimetric calculations. (Khan, F. M., Treatment planning II:
Data, Corrections, and Setup; in The Physics of Radiation Therapy,
2.sup.nd ed., 260-314, 1994) The use of the word CT in the
following descriptions is synonymous to any of the above commonly
used diagnostic devices.
The words CT and accelerator are used as an abbreviation for the
various diagnostic devices and the megavoltage radiation therapy
machines within the contest of their interrelations described in
this invention. The CT and the MRI are the most commonly used
diagnostic devices for radiation therapy planning. The linear
accelerator is the most commonly used megavoltage radiation therapy
machine.
An other major advantage of this invention is the dual usage of the
diagnostic device. The diagnostic device (CT) when not in use with
the megavoltage radiation therapy machine (accelerator) can be used
as stand alone diagnostic CT of a Radiology Department. This
enhances the cost-efficiency of this system and the cooperative
working environment of the Departments of Diagnostic Radiology and
the Radiation Oncology.
SUMMARY OF THE INVENTION
The present invention is a combined cost effective system for
diagnostic imaging and radiation therapy. The cost effectiveness of
radiation therapy component is achieved by means of reducing the
idle time of the accelerator during the usual working hours of the
day. It also increases the cost efficiency of the conformal
radiation therapy. The cost effectiveness of the imaging component
is achieved by its combined use as a diagnostic imaging device in a
Department of Radiology and as an accessory device for patient
setup and the on line verification of the intended treatment in a
Department of Radiation Oncology.
In this invention, any of the commonly used diagnostic imaging
devices can be used for the initial patient setup and verification.
Such imaging devices include but are not limited to CT, MRI, US,
tomographic X-ray, and the nuclear medicine imaging devices such as
the SPECT and PET scans.
To achieve this purpose, the invention is provided with an
accelerator in the accelerator room that is connected to multiple
CT in the adjacent CT rooms. The accelerator room is connected to
the CT rooms either by openings in the common wall of the
diagnostic rooms and the accelerator room or by means of an
ante-room to the accelerator room to which the CT room's doors
opens. A patient at a desired treatment position on the diagnostic
table in the CT room is moved to the accelerator table in the
accelerator room or visa versa through the wall opening or through
the ante- room of the accelerator. After the patient's transfer to
the desired room, the wall opening or the door to the ante-room is
isolated with a radiation protective door of desired material and
thickness. With the door closed, both rooms function independently
of each other. The patient is treated in the accelerator room while
the next patient's setup and its on-line verification proceeds in
the CT room. After completion of radiation therapy in the
accelerator room, the patient leaves the accelerator room through
its common entry and exit door. The patient for desired treatment
setup enters the diagnostic room through its common entry and exit
door. After the patient's setup is verified in the diagnostic room,
the door is opened for the patient's transport to the accelerator
room. The patient setup and the desired treatment verification is
much more time consuming than the actual delivery of the radiation
by the accelerator in the accelerator room. Since multiple CT are
connected to the accelerator room, a patient whose setup and
treatment verification is completed in any of the multiple CT room
is transferred to the accelerator room while other patient's setup
and verifications are in progress in other CT rooms. This
configuration of accelerator and the CT allows more patients to be
treated with a single accelerator. When the CT is not in this
combined use with the accelerator for radiation therapy of cancer
patients of the Radiation Oncology Department, it is used for the
routine diagnostic studies of patients of the Diagnostic Radiology
Department.
Another object of this invention is the provision of a patient
transport mechanism from the CT room to the accelerator room
without changes in the verified patient's treatment setup position
by the diagnostic device. It is being done by aligning and latching
together the diagnostic table with an extension table or the
accelerator table and transferring the flat table top insert with
the patient from one table to the other by rolling it to the
accelerator table.
A further object of this invention is the provision of both
manually controlled and motor driven radiation protective shutter
for opening and closing of the wall opening. With the shutter
closed, the accelerator and the diagnostic device can function
independently of each other. With an open shutter, the patients is
transferred from one room to the other. The facility safety
interlocks of the accelerator and the diagnostic device's control
console is connected to the shutter to assure safety from the
scattered radiation. If the shutter is not fully closed, a warning
red light will come up and the machines will not operate to produce
radiation.
A still further object of this invention is the provision of maze
wall arranged accelerator room to reduce the radiation energy that
reaches the wall openings for the connection with the diagnostic
device. In this instance the shielding requirement for these
openings is treated like that for the accelerator door where
multiply scattered radiation with much reduced energy is
encountered. With maze walls, the accelerator room is configured
with an ante-room in front of it. Patients are transported from the
CT room to the accelerator's ante-room space first and then to the
accelerator table by means of connecting tables.
A still further object of this invention is the increased
accelerator usage by separating the more time consuming patient
setup for treatment and treatment portal verifications from the
accelerator.
A further object of this invention is the daily on-line
pre-treatment verification of the previously planned treatment by
daily single or multiple slice check CT with superimposed isodose
treatment plan for conventional radiation therapy and for
3DCRT.
Another object of this invention is the provision of an alternate
configuration with multiple accelerators combined to the CT to
allow both the routine radiation therapy and special purpose
radiation therapy such as the stereotactic radiosurgery.
One other object of this invention is the provision of
CT-simulation of a patient for radiation therapy with a diagnostic
imaging CT that is connected to the accelerator in a manner as to
allow the patient transport from the CT table to the accelerator
table without any changes in the patient setup done by the CT.
Another major object of this invention is the use of the CT in
combination with the accelerator for radiation therapy by the
Radiation Oncology Department and as the diagnostic device for
diagnostic imaging by the Diagnostic Radiology Department.
BRIEF DESCRIPTION OF THE DRAWINGS
Other objects and advantages of this invention will become more
apparent from the specification taken in conjunction with the
accompanying drawings, in which:
FIG. 1 is a view of the centrally located accelerator connected to
three CT, through the wall openings with the shutter moved to the
side of the wall at both sides of the rooms.
FIGS. 2A-C show the sectional views of a modified commercially
available CT table for patient transport through the wall opening
and the closed wall after the patient has been transferred from one
room to the other.
FIGS. 3A-D show sectional and cross sectional views of a modified
CT table.
FIGS. 4A and B illustrate the sectional and cross sectional views
of a modified accelerator table.
FIGS. 5A-D demonstrate the sectional views of attachment of track
and grooves to the section B of the CT transport system for
movement of patient on modified table top insert.
FIG. 6 shows the top view of the section B of the CT transport
system after removing the table top insert D. The guide rail insert
is aligned for insertion and fastening to the section B's existing
lateral side slots.
FIG. 7 illustrates a table top extension that is fixed on to a
small table which can be rolled in place for alignment and
fastening to the CT table. The other end of this table top
extension can be connected the corresponding end of a similar table
top extension from the accelerator room and brought in alignment
with each other through the wall opening.
FIGS. 8A-C illustrate the modifications made to the rearward end of
the accelerator table's section F and to the CT table's section B
to accommodate these two table's connections with each other. The
sectional view of the two tables connected together is also
shown.
FIGS. 9A-C demonstrate the transport of the modified flat table top
insert of the CT table section D and thereby also the patient from
the CT table to the accelerator table through the wall opening.
FIGS. 10A-C show the rotation of the accelerator table after the
modified CT table top insert, section D has been transferred on top
of it to 180 degree to bring the patient's upper body and the head
under the accelerator's treatment head in one configuration of the
CT and the accelerator placements in their respective rooms.
FIGS. 11A and B illustrate the complete assembly of the CT table
and the accelerator table with the modified flat table top insert
as the primary transport and which is moved forward to show part of
the secondary transport of the CT table and the accelerator
table.
FIG. 12 is an illustration of an other arrangement of the CT and
the accelerator to enable the treatment of a patient without
rotating the table in one instance and with table rotation in
another instance.
FIGS. 13A-C show a straight patient's transport from the CT to the
accelerator with patient's upper body and the head brought under
the accelerator's treatment head without table rotation and with
table rotation for the CTs that are placed at 90 and 270 degree
angles from the CT facing straight to the accelerator as in FIG.
12.
FIG. 14 is a modified embodiment of the invention wherein two
accelerators, one for the routine radiation therapy and the other
for special purpose radiation therapy is illustrated. After the
setup of a patient on the CT table, the patient is moved through
the wall openings to the respective accelerator table for desired
treatment.
FIG. 15 is the top view of an other configuration of a single
accelerator room connected to five adjacent CT rooms with their
respective openings and shutters in the shared CT- accelerator
wall
FIG. 16 illustrates the motor driven and the manual opening and
closing of the sliding shield door and screws and support for
attachment of additional thickness lead shields than the calculated
thickness if after testing it is found to be necessary.
FIG. 17 shows the cross section of the top of the sliding shield
door with metal fasteners, guide and rollers.
FIG. 18 demonstrates the cross section of the bottom section of the
sliding shield door with its metal fasteners, wheels and metal
channel.
FIG. 19 shows the sliding shield door made of liquid shielding
material with its hollow core door, reservoirs for the liquid
shielding material, the pumps, the pipe line and the door's sliding
mechanism.
FIGS. 20A-C illustrate the top section of the opening and closing
valves for control of the filling with of the hollow core of the
sliding shield door with the liquid shielding material.
FIG. 21 shows the core of the sliding shield door after filling
with the liquid shielding material and valve in its closed
position.
FIG. 22 demonstrates the sectional details of the bottom of the
multi-cell sliding shield door. The outlet valve is shown as in its
closed position.
FIG. 23 and FIG. 24 illustrates the sectional views of the top and
the bottom of a single cell sliding shield door.
FIG. 25A and B show a rotating cylindrical shield with a central
opening. It is fixed to the wall opening and brought to the open
position or closed positions by a 90 degree rotation.
FIGS. 26A and B show the views of the sliding shield door from the
accelerator room's side and the diagnostic room's side.
FIGS. 27A and B show the accelerator side's sliding shield door
filled with the liquid shielding material and the diagnostic room
shielded with a single sheet of sliding shield door.
FIG. 28 illustrates an accelerator room with maze walls to reduce
the energy of the radiation reaching to the opening of an ante-room
space of the accelerator room. It drastically reduces the shielding
requirement at the wall openings and allows to treat them as the
door opening of a medical accelerator room. Multiple diagnostic
devices and ancillary rooms for procedures such as surgery are
attached to the common walls of these rooms with the wall of the
accelerators ante-room space. The patient's transport from the
diagnostic rooms table to the accelerator table is facilitated with
an extension table that can be rolled on rails attached to the
floor.
FIG. 29 is an other illustration of the same configuration of the
structural features as in FIG. 28 but with modified maze wall 94
with no central opening and with the bending tracks on floor to
circumvent the maze wall 94, to enter the accelerator room.
FIG. 30 is yet an other illustration of an accelerator surrounded
my maze wall and the diagnostic devices attached to its hexagonal
perimeter walls with openings for the patient's transport. This
arrangement also reduces the energy of the radiation reaching the
wall opening in the perimeter walls. It allows to treat these wall
openings as for a medical accelerator's door design with much
reduced shielding.
FIG. 31 illustrates two accelerators one at each ends of the
ante-room and with multiple diagnostic devices. One megavoltage
machine is configured closer to a surgical room and is equipped
with special purpose collimator for special purpose megavoltage
radiation therapy. The other megavoltage machine at the other end
of the ante-room is without such modification and is for
conventional radiation therapy.
DETAILED DESCRIPTION OF THE INVENTION
Referring to the drawing shown in FIG. 1, numeral 1 designates a
commercially available medical accelerator and its treatment table
2. It is housed in the accelerator room 3 which is constructed with
required thickness radiation shielding material. The accelerator
room has its entrance door 4, and wall openings 5, through which it
is connected to the adjacent CT rooms 6, each containing a
commercially available CT 7, and its table 8. The connecting wall
openings between the accelerator room and the CT rooms are opened
and closed with sliding shield doors 9. Both sides of the wall
openings are fitted with sliding shield doors 9. These sliding
shield doors are made of required thickness radiation protective
material of a suitable kind. Doors 10 are for entrance to and exit
from the CT rooms. The accelerator room's shielding walls 11 and
the CT room's shielding walls 12 are constructed with the
appropriate thickness shielding material based upon the photon
beam's energy. Since the accelerator's photon beam is in the range
of MeV and the CT's photon beam is in the range of KeV, the
accelerator's walls 11 have much higher wall thickness than the CT
room's walls 12.
In FIGS. 2A-C, a commercially available CT's integration for its
use with the accelerator is shown. FIG. 2A shows a commercially
available CT as it relates to this invention. The CT table's cradle
13 moves forward towards the gantry's central opening 14, and
backward on its intermediate support 15. Commonly a flat table top
insert 16 for placement of a patient on a flat surface on top of
the CT table's cradle 13, for radiation therapy planning CT scans
is used to reproduce the same outlines of a patient's body contour
as the one that would result when the patient is placed on the flat
table top of an accelerator table. According to this invention, the
table top insert 16 is modified to be identical to the table top 17
of an accelerator table and for use as a common table top for the
accelerator and the CT tables. A gantry 18 with a central opening
14 having a diameter of about 70 cm is generally used for a
radiation therapy planning CT. The opening accommodates both the
patient and the devices used for the patient's settings for
radiation therapy. As shown generally in FIG. 2B and 2C are the
opened and closed wall openings. FIG. 2B shows the modified table
top insert 17 extended through the center wall opening 5 towards
the accelerator room. FIG. 2C shows the closed wall opening without
the table top insert 17 on the CT table's cradle 13 to indicate the
modified table top 17 has completely moved to the accelerator room.
In FIG. 2B, the opened wall opening 5 with the table top insert 17
extended through it is shown. The shield door 9 is slid away from
the wall opening 5 and is brought to its open position 9a. The
forward movement of the CT cradle 13 along with the table top
insert 17 and the stationary CT table's intermediate support are
also shown in FIG. 2B. After completion of the passage of the table
top insert 17 from the CT room to the accelerator room through the
wall opening 5, the sliding shield door 9 is slid to its closed
position 9b as shown in FIG. 2C. The CT table's cradle 13 is
retracted and is brought to rest on the CT table's intermediate
support 15 as illustrated in FIG. 2C.
In FIG. 3, the sectional view of the CT table with the modified
flat table top insert 17 and the CT table's cradle 13 and
intermediate support 15, with their cross sectional view through
plane A--A is shown. FIG. 3A shows the modified table top insert.
Similar to a commercial accelerator's table top, the modified table
top insert 17 has portions for mylar insert 19, a wood top 20, a
tennis racket opening 21 and its non-metallic frame 22. The
cross-section through plane A--A is further illustrated in FIG. 3C.
In FIG. 3B, a commercial CT table and its association with the
modified table top insert 17 is illustrated. The table top insert
17 is made to fit on the CT table's cradle 13 and to roll on it.
The table top insert 17, the cradle 13 and the intermediate support
15 rest on the top of the table elevator and base assembly 23. The
cross section through line A--A is further illustrated in FIG. 3C
wherein the cross sectional view of the modified table top insert
17, through line A--A of FIG. 3A is shown. The bottom of the
modified table top's frame 22 is fitted with two sets of rollers 24
for its guided movements on the CT table and the accelerator
tables. The section through the tennis racket 21 of the modified
table top insert 17 is also shown. In FIG. 3D, the modifications
made to the commercial CT table's cradle 13 through plane A--A as
illustrated in FIG. 3B are demonstrated. Both lateral top surfaces
of the cradle 13 are modified by forming longitudinal non-metallic
guide grooves 25 on which the rollers 24 of the modified table top
insert 17 can travel. The fitting of the longitudinal guide grooves
within the cradle is further illustrated in FIG. 5,6,7 and 8. At
the end of the CT table's cradle 13 two female notches 26 are
fitted for connection with the extension table. The guide grooves
25 and the female notches 26 of the cradle, the intermediate
support 15, and the elevator and base assembly of the CT table 23
are shown in the cross sectional view of the CT table at A--A plane
of the FIG. 3B.
FIG. 4B illustrates the sectional view of the modified flat table
top insert 17 with a modified accelerator table and their cross
section through the plane B--B of FIG. 4A. In FIG. 4A, the
accelerator table's top most portion where the patient is placed
for treatment is removed and replaced with the traveling modified
table top insert 17 which has the identical structural components
as the usual accelerator table top, such as the mylar 19, wood 20,
tennis racket 21, and the non-metallic frame 22, but it is also
fitted with rollers 24 underneath it for its travel from the CT
table to the accelerator table and visa versa. Beneath the table
top insert 17 is shown a commercial accelerator table. Like the CT
table, the commercial accelerator table also has a cradle 27 and an
intermediate support 28, but with a slightly different
configuration. After removing the commercial accelerator table
top's mylar wood and tennis racket, its two side rails 29 (FIG. 4B)
are exposed and on which two frames 30 with side grooves 31 are
fitted for the travel of the rollers 24 of the modified table top
insert 17. The grooves on this frame and those fitted on to the CT
table's cradle are aligned to make it a continuous path for the
smooth travel of the rollers 24 of the modified table top insert 17
as shown in FIG. 8. At the rear end of the accelerator table's
cradle two male notches 32 are fitted interconnectingly with female
notches 26 (FIG. 3D at the rear end of the CT table's cradle 13.
The accelerator table's cradle 27 and the intermediate support 28
rest on its elevator and base assembly 33.
The cross sectional views at plane B--B through the modified table
top insertion 17, accelerator cradle 27, intermediate support 28,
and the elevator and base assembly 33 are shown in FIG. 4A. In the
cross sectional view as in FIG. 4B the modified table top insert
17, with its frame 22, the mylar 19, and its rollers 24 as aligned
to the grooves 31 (FIG. 4A) of the accelerator frame 30 (FIG. 4B)
are illustrated through the plane B--B of FIG. 4A. In FIG. 4B the
cross sectional view through the plane B--B of the accelerator
table is illustrated. The side rails 29 of the accelerator table's
cradle 27 are fitted to a frame 30 with side grooves 31 for travel
of the rollers 24 of the modified table top insert 17. The male
notch 32 on the frames 30 for connection with the female notches 26
of the CT cradle 13 (FIG. 4A) and the accelerator table's elevator
and base assembly 33 are also shown. As described earlier, the
frames 30 are fitted to the accelerator's table top after removal
of its wood 20, mylar 19, and the tennis racket 21, (FIG. 4A).
The sectional drawings in FIG. 5A-D show the prefabricated track
insert 34 and flange 35 with grooves 25 for the modified flat table
top insert's 17 rollers 24 to travel on the CT table's cradle 13,
its fitting to the cradle's existing fastener site 36, and the
continuous grooves 25 on CT table's cradle 13. In FIG. 5A, the
existing fastener site 36 and its wedge like flange 37 on the CT
table's cradle 13 is generally used to insert fasteners to its slot
38 for the secure positioning of a patient on the cradle. The
fastener is attached to the hollow under surface created by the
wedge like flange 37 of the fastener site. The modification
introduced to this existing fastener is shown in FIGS. 5B, C and D.
In FIG. 5B, the slot 38 is made to accept a similar but reversed
flange 35 from a prefabricated track insert 34. The arrow indicates
the direction by which the prefabricated track insert 34 is fitted
to the existing fastener site 36 of the CT table's cradle 13. In
FIG. 5C the completed assembly of the prefabricated track insert 34
with the preexisting fastener site 36 at the CT table's cradle is
shown. The reversed flange 35 of the prefabricated track insert is
brought underneath the flange 37 of the CT cradle's existing
fastener site 36 and is firmly fitted together. Fastening of a
longitudinal prefabricated track insert to the CT cradle's existing
longitudinal fastener site 36 creates a continuous groove 25 on top
of the CT cradle. (See also FIG. 6.) A pair of continuous grooves
25 secured with screws 39 onto the CT cradle's lateral elevations
are illustrated in FIG. 5D. The female notches 26 at the end of the
CT cradle for connection with the table extension are also shown
here. The CT cradle's rear end 44 and its relation with other
connecting tables to make a continuous connection from the CT table
to the accelerator table are best shown in FIG. 7.
FIG. 6 shows a top longitudinal view of the CT table's cradle 13
with its existing fastener sites 36 on both of its lateral sides.
The modified flat table top insert 17 which sits on top of the
cradle is removed to illustrate this longitudinal top view of the
CT table's cradle. The arrows on both sides of the cradle indicate
the longitudinal prefabricated track insert 34 as aligned for
insertion into its existing fastener site's slots 36 to establish
the continuous longitudinal grooves 25 on top of the CT cradle for
the modified flat table top inserts 17 rollers 24, forward and
backward. The configuration of these grooves 25 on top of the CT
cradle 13 is further illustrated in the sectional drawing at the
bottom of the FIG. 5.
FIG. 7 illustrates a table top extension 40 on top of an extension
table 41 placed in the CT room as a means to create an extension of
the CT table towards the accelerator room through the wall opening.
Its forward end 42 is fitted with two male notches 43 which are
identical to the accelerator table's cradle end's male notches 32
(FIG. 4 and 8). It connects with the corresponding female notches
26 at the rearward longitudinal end 44 of the CT cradle. These
connecting notches are brought in alignment and fastened with the
female notches 26 at the rearward end 44 of the CT table's cradle.
Both table ends are further firmly attached with a latching clip 45
at the under surface of the table extension and with the clip
fastener 46 at the CT cradle's under surface. The other end 47 of
this table extension can reach the center of the wall opening 5.
This end 47 of the table extension is fitted with two female
notches 26 and a clip fastener 46 which are identical to those at
the CT cradle's connecting end 44. This end 47 can be connected to
the two male notches 43 from the rearward end 48 of an extension
table from the accelerator room. These male notches are identical
to the male notches 43 of the extension table in the CT room and
the accelerator cradle's rearward end's male notches. All these
male notches are identified by the numeral 43. After the connection
with the rearward end of the extension table from the accelerator
room 48 with the rearward end of the extension table from the CT
room 47 they are firmly fastened with a latching clip 45, at the
rearward end of the extension table from the accelerator room and
by the clip fastener 46 at the rearward end of the extension table
from the CT room. The latching clips 45 and the clip fasteners 46
are identical for the extension tables, accelerator cradle's end
and the CT tables cradle end, and hence they are identified by the
same numeral 45 for the latching clip and 46 for the clip fastener.
Both table top extensions are brought to the center of the wall
opening 5 for this firm connection with each other. The opposite
end 49 of the table extension from the accelerator room facing the
cradle end of the accelerator table with its female notches 26 and
the clip fastener 46 is similarly connected with the rearward end
50 of the accelerator table's cradle by attaching the accelerator
table end's male notches 32 with the female notches 26 of the
extension table's end 49 and fastening them together with the
latching clip 45 and the clip fastener 46. The projecting male
notches 32 and 43 of the table ends 50 and 42 are slid back when
tables are not connected and pushed forward when these table end's
connections are needed. These connections and the fastening of the
extension table from the CT room with the CT cradle on one side and
with the extension table from the accelerator room with the
extension table from the CT room through the wall opening and its
final connection with the accelerator table's cradle end in the
accelerator room on the other side provides the continuity of the
table from the CT table's cradle to the accelerator table's cradle.
This facilitates the establishment of the continuous grooves 25
from the CT cradle 13 in the CT room to the accelerator cradle 27
in the accelerator room (FIG. 8). The flat table top extension 17
can be rolled towards the accelerator room or to the CT room over
these continuous longitudinal grooves 25 which are now connected
with the CT cradle and to the accelerator cradle through the wall
opening (FIG. 9 and 10). After a patient on the modified flat table
top insert 17 is rolled from the CT cradle in the CT room to the
accelerator cradle in the accelerator room through the wall opening
5, the extension tables are disconnected from each other and from
the CT cradle and the accelerator cradle, and they are moved away
from the wall opening. The sliding shield door 9 at the side of the
accelerator room and the other sliding shield door at the side of
the CT room are moved to close the wall opening from both sides as
in FIG.2.
FIGS. 8A-C are an illustration of the modifications to a
commercially available accelerator table's cradle's rearward end's
50 for its connection with either an extension table's female
notches 26 or with the CT cradle's rearward end 44. FIG. 8A is an
illustration of the modifications made to the accelerator table end
50. It is fitted with two frames 30 on top of its each side rails
29 of the accelerator table's cradle 27. These frames contain
grooves 31 which are symmetrical to the CT table's prefabricated
track insert's groove 25 (FIG. 5B and 8B). The modified flat table
top insert 17 travels on the grooves 25 of the CT table's cradle 13
and on the grooves 31 of the accelerator table's cradle 27.
Symmetry of these grooves enables the flat table top insert 17 to
travel on top of both these tables smoothly. The sectional view of
the CT cradle's rearward end 44 with the prefabricated track 25
firmly attached to it is also shown in FIG. 8B. Its side by side
illustration with the accelerator cradle's modified rearward end 50
is to demonstrate their connections to each other as shown in FIG.
8C Alternatively, these table ends can also be connected to the
connecting ends of an extension table (FIG. 7). In this
illustration, the modified accelerator cradle's 27 end 50 with the
male connectors 32 (FIG. 8A) is attached to the CT cradle's 13
female notches 26 at the CT table's end 44 (FIG. 8B). These table
ends are firmly fastened together with latching clip 45 and clip
fastener 46, (FIG.7). After these connections, the accelerator
table's side grooves 31 on its frame 30 become a continuous groove
with the CT cradle's side grooves 25.
In FIGS. 9A-C the patient transport from the CT table in the CT
room to the accelerator table in the accelerator table is
illustrated. The modified flat table top insert 17 is fitted with a
head holder 51 and rests on the CT cradle 13 in position 52, in
FIG. 9A It is slightly advanced towards the wall opening and the
accelerator table 2. For illustration purposes, this initial
position is indicated as 52 in FIG. 9A. In FIG. 9B the flat table
top insert on CT cradle is rolled further towards the wall opening
and the accelerator table 2 and brought to position 53. This
continuous forward advancement of the modified flat table top
insert towards the wall opening 5 and the accelerator table 2 is
further illustrated in FIG. 9C. The flat table top insert passes
through the wall opening 5 reaching the accelerator table by its
forward advancement over the accelerator table's cradle 27. It is
thus brought to about the half way point over the accelerator
cradle in position 54.
FIGS. 10-C demonstrates the continuous forward advancement of the
flat table top insert 17 over the accelerator table's cradle on the
grooves 25 of the CT cradle and 31 of the accelerator cradle as in
FIG. 10A and FIG. 10B. In FIG. 10B the flat table top insert is
transferred completely to the accelerator table 55. Afterwards a
180 degree accelerator table rotation is made to bring a patient's
upper body portion with the head holder 51 directly under the
accelerator's treatment head when this region is to be treated, see
FIG. 10B The arrow 56 indicates the 180 degree rotation of the
accelerator table. After the 180 degree rotation of the accelerator
table, the head holder 51 is brought to the opposite end of the
accelerator table as shown in FIG. 10C. in this bottom drawings.
The wall opening and the CT in the opposite CT room is also shown.
FIGS. 9A-C and 10A-C thus show a patient's continuous transport
form the CT table to the accelerator table and the subsequent
rotation of the accelerator table to bring the patient to the
desired treatment position without altering the patient's position.
In between the CT table and the accelerator table, the extension
tables are placed as needed as shown in FIG. 7. In these
descriptions the movements of the flat table top insert 17 on the
grooves of the CT cradle 13, extension tables 41, and on the
accelerator cradle 27 correlate to the transport of a patient on
top of the flat table top insert 17. For patients whose setup and
verifications were done with the CT placed at 90 and 270 degree
angles to the accelerator, only a 90 degree rotation of the
accelerator table is required to bring the patient under the
accelerator's treatment head.
FIGS.11 A and 11B show the end views of the CT and the accelerator
tables with the modified flat table top insert above. Both tables
are modified for the travel of the modified flat table top insert's
rollers 24 over the grooves 25 of the CT cradle 13 and grooves 31
of the accelerator cradle 27. The modified table top insert's mylar
19, wood top 20, tennis racket 21, and its non-metallic frame 22
are identical to those of a commercial accelerator's table top on
which the patients are placed for treatment. FIG. 11A is the CT
table with the modified table top insert 17 on the grooves 25 of
the CT table's cradle 13. At the rearward end of the CT cradle, two
female notches 26 for connection with the accelerator table's
cradle are also shown. The CT table's intermediate support 15,
cradle 13, and the modified flat table top support rest on the
elevator and base assembly 23 of the CT table.
FIG. 11B shows the modified accelerator table with the modified
flat table top insert 17 on top of the accelerator table's cradle
27. The regions of this modified table top insert 17, the mylar 19,
wood 20, tennis racket 21, frame 22, the rollers underneath it 24
are all identical to the flat table top insert 17 on top of the CT
table's cradle 13. The grooves 31 on accelerator table's cradle 27
are symmetrical to the grooves 25 on the CT table's cradle 13. The
accelerator table's cradle's side rails 29 are fitted within the
frame 30 with its grooves 31 on which the rollers 24 of the
modified flat table top insert 17 can be rolled to the CT cradle or
visa versa. The accelerator table's intermediate assembly 28, the
cradle 27, and the modified flat table top insert 17 rest on the
accelerator table's elevator and base assembly 33.
FIG. 12 is an illustration of another arrangement of the CT and the
accelerator to enable the treatment of a patient without rotating
the table in one instance and with table rotation in another
instance. In first instance, the CT facing directly opposite to the
accelerator's gantry 57 is placed in the CT room with the back side
of the CT gantry 58 facing the wall opening 5. It is aligned with
the wall opening for the forward transport of a patient on the
modified flat table top insert through the CT's central opening and
the wall opening to the accelerator table. As described above, an
extension table 41 can be placed in between the CT's central
opening's back side 59 and the wall opening 5. In the accelerator
room, a similar extension table can be placed in between the wall
opening and the accelerator table. With this arrangement a patient
is first setup on the CT table and after the treatment port
verification with the CT, the patient is then advanced forward
through the CT's central opening's back side 59 and through the
wall opening 5 to the accelerator room and to the accelerator table
and placed directly under the accelerator's treatment head without
a 180 degree rotation. If the CT is placed with its gantry's front
facing the accelerator directly as shown in FIG. 1 and 14, and the
patient's head is placed on the CT table with the head closer to
the gantry and the foot at the rearward end of the CT cradle, the
accelerator table needs to be rotated to 180 degree after the
patient is transferred to the accelerator room to bring the
patient's head region under the accelerator's treatment head. If a
patient is placed on a commercially available CT table with the
foot at the gantry end and the head at the table's rearward end,
the CT of the head and the upper portions of the body can also be
done. For this, a three foot extension to the forward end of the CT
cradle may be needed. By doing so, portions of the head may not be
in the CT plane. This is a major disadvantage, particularly for
head and neck region's treatment. The straight transport of the
patient either by reversing the position of the patient with the
foot facing the gantry or by reversing the CT with the back of the
CT gantry's central opening 59 facing the accelerator and moving
the patient through the CT's back central opening to bring the
patient's treatment region under the accelerator's treatment head
eliminates the need for the accelerator table's rotation. This
elimination of the table rotation further enhances the quality of
conformal radiation therapy and the stereotactic radiosurgery.
However as noted above, the reversing the position of the patient
with the head away from the CT's gantry may not be suitable for
this kind of treatment to the head and neck region. The CT
positioned at 90 and 270 degree to the accelerator as in the second
instance, will function as a combined unit with the accelerator by
rotating the accelerator table to 90 degree to bring the patient
under the accelerator's treatment head.
FIGS. 13A-C further illustrate the direct transport of the modified
flat table top insert 17 from the CT cradle 13 towards the
accelerator table's cradle 27, through the CT gantry's central
opening's front 14, and its back 59, and wall opening 5. The table
top insert is rolled over to the accelerator table's cradle 27, see
FIG. 13A In this instance, no 180 degree rotation of the
accelerator table is necessary to bring the patient's treatment
site under the accelerator's treatment head as in FIGS. 10A-C. If
the CT facing directly opposite to the accelerator is placed with
the front of the gantry facing the accelerator (FIG. 1, 14) and the
patient is placed in the usual manner with the head in the head
holder which is closer to the gantry and the foot at the rearward
end of the CT table, then a 180 degree rotation of the accelerator
table is required to bring the patient's head with the head holder
48 under the accelerator's treatment head. With the presently
available commercial CTs, a reverse patient's setup on CT table
with the patient's head away from the gantry's central opening is
impractical since the difficulties associated with the geometrical
positioning of the head for its satisfactory scanning. In this
position however the scanning of the upper portions of the body can
be done by attaching an extension of about three foot to the CT
cradle's forward end and placing the patient in a manner to make
use of this table extension. By doing so, a patient after setup and
scan can be transferred to the accelerator table and brought under
the accelerator's treatment head without the accelerator table's
rotation, see FIG. 13B In contrast to this direct transport of the
modified flat table top insert 17 towards the accelerator's
treatment head, FIG. 13C shows a 90 degree rotation 60 of the
accelerator table to bring the patient under the accelerator's
treatment head when the CTs are placed at 90 or 270 degree (FIGS.
1, 12, 14) to the accelerator. For critical procedures such as the
conformal radiation therapy and the stereotactic radiosurgery, the
ability to bring the patient's treatment site without this rotation
is an added advantage for precise positioning of the patients and
for the delivery of the planned treatment precisely.
The configuration as shown in FIG. 14 with two accelerators 1 and
61, two CTs 7 and the CT tables 8, with respective openings 5 in
the walls for transport of the modified flat table top insert 17
with the patient's head holder 51, the accelerator tables 2, and
the sliding shield doors 9, facilitate the routine daily radiation
therapy with one accelerator 1 and the specialized treatment such
as the stereotactic radiosurgery with other accelerator 61. In this
case, the second accelerator 61 can be used as a dedicated one for
special procedures such as the stereotactic radiosurgery,
intraoperative radiation therapy and conformal 3D radiation
therapy. After the setup and verification of a patient on the CT
table, the patient can be transferred to the accelerator table
through the back side of the CT gantry's central opening 59, and
through the wall opening 5 directly described above, without any
need for the accelerator table's rotation.
Permanently or semi-permanently, this special purpose accelerator
61 can be equipped with the necessary field shaping collimator 62
for special procedures such as the stereotactic radiosurgery or
intraoperative radiosurgery at those Radiation Oncology centers
where these procedures are frequently done. Of course both these
accelerators 1 and 62 can be fitted with the special field shaping
collimators and can be used for the special procedures. The
advantage of equipping one accelerator in the configuration as with
the accelerator 61 with the CT in this FIG. 14 is that it can take
the full advantage of the CT combined accelerator to improve the
quality and the cost efficiency of such treatments. It improves the
patient setup and field verification, eliminates the waiting time
for access to an accelerator and the dead time for CT data transfer
from the Radiology department to the Radiation Oncology department
for treatment planning. At a Radiation Oncology Department where
many stereotactic radiosurgeries are done, the weekly number of
such procedures is limited to about four patients. It is because of
the waiting for access to an accelerator, delay in CT data transfer
from the Radiology department to the Radiation Oncology department
for treatment, planning and the subsequent efforts to set up the
patient on the accelerator table identically as the CT images was
obtained at the Radiology department's CT. Excluding the waiting
time for the access to the accelerator, the present turn-around
time for the stereotactic radiosurgery is about four hours. The
technical improvements of this invention not only reduces the
turn-around time from four patients a week to many more, but also
improves the quality of the treatment significantly. The
improvement of the quality of this treatment is much more important
than the cost savings. This invention significantly improves both
the quality and the cost efficiency of these specialized radiation
therapy and therefore makes them available to a large number of
patients everywhere. The special field shaping collimator can also
be fitted on to the accelerator setup as in FIG. 12 but at a
sacrifice of accelerator time for the frequent change of the field
shaping collimator and the need to wait for access to the
accelerator until the daily regular patient's treatment have been
completed.
The patient transport to the accelerator table and bringing the
patient under the accelerator's treatment head from the CT facing
directly to the accelerator 1, and the CT placed at 90 degree to
the accelerator 1, is performed by a 180 degree rotation in the
former instance and with a 90 degree rotation in the latter case.
It is further described under FIGS. 10A-C and 12.
In FIG. 15, a different configuration of a single accelerator room
with four CT 7, connected to it is shown. In this configuration,
the accelerator 1 is centrally located, and the four CTs 7
surrounds it. As in FIG. 1, the wall openings 5 are opened and
closed with sliding shield doors 9. The general operational
features for the patient transport from the accelerator room to the
CT rooms through the wall openings and bringing the patient under
the accelerator's treatment head are generally as described in the
transportation of the table top insert with the patient on an
extension table. The main purpose of this illustration is to
demonstrate that several CTs can be added to this CT combined with
the accelerator for the cost efficient and improved quality
radiation therapy of cancer and for the routine diagnostic
imaging.
FIG. 16 illustrates the motor driven and the manual opening and
closing of the sliding shield doors made of radiation protective
metals and screws and its support mechanism. Provision is given for
attachment of multiple slabs of heavy metal sheets 9c to make the
weight of this mobile door to be distributed among the multiple
individual metal sheets at the accelerator side's wall opening. At
the side of the imaging room a single slab metallic sliding shield
door 9d (FIG. 26) is attached as this is sufficient for the
radiation protection from the diagnostic x-ray machine's kVp range
of photon's energy and from the scattered radiation from the
sliding shield door at the side of the accelerator room. The
required thickness of the metallic sliding shield door is
calculated based upon the common formulas integrating the workload
(W), use factor (U), occupancy factor (T) and the distance (d). The
wall opening for the transport of the patient from the CT room to
the accelerator room is placed in the secondary barrier wall (Khan,
F. M., Radiation protection; in The Physics of Radiation Therapy,
2.sup.nd ed., 474-503, 1994; Shleien, B., Exposure and shielding
from external radiation; in The radiation Physics and Radiological
Health Handbook, 163-218, 1992).
The cross sectional view in FIG. 16 illustrates the sliding shield
door as mounted on to the concrete wall. The metal channels 63 in
the lower section of the concrete wall 65 and similar metal
channels 64 in the upper section of the concrete wall 65 serve as
the guide for the sliding door 9. It is fitted with a mechanical
handle 66 to move to the opened and closed positions of the wall
opening 5. The lower section of the sliding shield door is fitted
with metal fasteners 67 as is further illustrated in FIG. 18. This
door is compartmentalized as a series of slabs of doors which can
be adjusted according to the required amount of shielding material
needed for a particular sliding shield door. Also more of the
weight of the shielding material is shared by these slabs than if
the mobile door were made of a single compartment. The sliding
shield door is driven to the open and closed positions by a motor
driven mechanism when the weight of the sliding shield doors
exceeds the limit that can be easily pulled and pushed by hand.
Alternately to the sliding shield door, a conventional medical
accelerator's beam shield can be adapted as sliding from one end of
the wall opening to the other for the opening and closing of the
wall opening with adequate shielding similar to the sliding shield
door.
In FIG. 17 the cross section of the top of the sliding shield door
is shown the door is comprised of the metal fasteners 68 with its
guide 69 for its rollers 70 to slide through the metal channel 64.
The shielding material 71 is threaded into the metal fastener 68.
The top section of the sliding shield door is shown as attached to
the upper portion of the concrete wall 65.
FIG. 18 illustrates the cross section of the bottom portion of the
sliding shield door. Its metal fasteners 67 are fitted with
vertically installed wheels 72 for the sliding shield door's travel
through the metal channel 63. The shielding material is screwed
into the lower metal fasteners 67. This lower section of the
sliding shield door is fitted on to the lower portion of the
concrete wall 65.
In FIG. 19 an alternate method of constructing the sliding shield
door is shown. In this case the shielding material is in liquid
form which runs to the hollow core of the sliding shield door 73
which is installed with a set of inlet 74 and outlet 75 hoses. The
core of this sliding door is divided into multiple cells. The
number of cells filled with the liquid shielding material is based
up on the required shielding for a given energy radiation and the
position of the wall opening in relation to the accelerator.
Whenever the wall opening 5 needs to be closed, the sliding hollow
core door is pulled towards the wall opening and the hollow core
door is kept in its locked position and filled with the liquid
shielding material. The liquid shielding material is allowed to run
from a reservoir 76 in the concrete wall at the top of the wall
opening by opening the valve 82 (FIGS. 20 and 21) and through the
hose 74 into the multi-cells of the sliding hollow core door. The
valve 84 inside the hollow core door controls the fillings of the
individual cells 86, 87, 88 (FIGS. 20,21). Simultaneously, the
multi-cell's outlet valve 91 (FIG. 22) is closed to prevent the
flow of the liquid shielding material through the outlet hose 75 at
the bottom of the sliding hollow core door. The core of this hollow
door is allowed to fill with the liquid shielding material 93 (FIG.
21). After filling the hollow core door with the liquid shielding
material the flow valve 84 is brought into the closed position as
in FIGS. 20 and 21. Simultaneously, the outlet valve 82 of the
upper reserve tank is also brought to its closed position (FIGS.
20, 21 and 23). When the wall opening 5 is to be opened, the drain
valve 91 (FIG. 22) at the bottom of the sliding hollow core door is
released and the liquid shielding material is allowed to flow
through the outlet hose 75 to a drain tank 78 located below the
wall opening 5 in the concrete wall. The sliding hollow shield door
is then moved away to the side of the concrete wall to open the
wall opening 5. The sliding hollow core door rests upon its side on
a metal channel 79. The door is fitted with rollers 92 and guide 80
(FIG. 21) to slide this door to open or close the wall opening 5.
The clamps 83 are used to attach the loose mid portions of the
hoses 74 and 75 to the top and the bottom of the sliding door so
that they will not interfere with the movements of the sliding
door. Two succession pumps in the concrete wall 77, one at the
bottom and the other at the top of the wall opening 5, are
connected to each other with a pipe line 81. The liquid shielding
material is pumped from the draining tank 78 to the top reservoir
76 for the refilling of the sliding hollow core door for the next
time when it is brought in position as a shield door in front of
the wall opening 5. Adequate lead sheets are placed in front of the
concrete where the fittings of the sliding shield door's accessory
equipment have created defects in the required wall thickness.
FIG. 20 shows the cross section of the top of the sliding door with
the inlet valve 82 which controls the individual cell's 86,87,88
filling with the liquid shielding material which flows through the
hose 74 to the hollow core of the sliding door. The inlet valve 84
is moved from one cell to the other for each cell's filling. In
FIG. 20A the filling of the first cell with the liquid shielding
material is shown. The first partial movement of valve 84 to the
right allows the flow of the liquid shielding material to the first
cell 86, through the first valve opening 85. In FIG. 20B, the valve
84 is moved further to the right to open the inlets 89 of the both
first and the second cells 86,87 to allow the flow of the liquid
shielding material into both these cells. In FIG. 20C, the valve 84
is moved further to the right to open the inlets 90 of all three
cells 86, 87, 89 to fill all of them with the liquid shielding
material.
By consecutive movement of the valve 84 towards the left, the
inlets of the third, second and the first cells 88, 87, 86 are
closed. Thus the cells are filled as one by one to meet the
required thickness shielding material in the sliding shield door.
It gives the flexibility to use the same multi-cell sliding hollow
core door at various sites with the site specific required
thickness shielding material. An alternative to the multi-cell
hollow core door is the multiple single cell hollow core door which
are connected individually to the reserve tank 76 and to the drain
tank 78 and is attached to individual metal channel 79, guide 80,
and the rollers 92. This arrangement gives the flexibility to
distribute the weight of the liquid shielding material to multiple
individual sliding hollow core doors. It is illustrated in FIG. 23.
Sensor switches attached to the lateral sides of the hollow core
door automatically stops the movement of the sliding door if it
encounters any obstruction in its path. Interlocks connected
between the sliding hollow core door and the accelerator assures
the radiation beam on only if the required cells are filled with
the liquid shielding material and the wall opening 5 is completely
closed. When multiple diagnostic devices are combined to an
accelerator, there will be multiple wall openings 5 as described
before. If any of the wall opening is in open position,
incompletely closed, or the sliding hollow shield door is
incompletely filled with the liquid shielding material, the
interlocks to the accelerator will prevent the accelerator from
activating to produce radiation. The commercial accelerators are
integrated with interlocks to check the status of the door opening.
This interlock is connected to the interlocks of the sliding shield
doors and the wall openings.
In FIG. 21, the top section details with the inlet valve 84 in its
closed position after filling the sliding hollow core door's cells
86,87,88 with the liquid shielding material 93 and the closed
position of the inlet valve 82 at the level of the inlet hose 74 is
shown. The metallic channel 79 is screwed on to the concrete wall
65. The guide 80 and the roller 92 for the sliding movements of the
door on the metallic channel are also illustrated.
FIG. 22 illustrates the sectional details of the bottom of the
sliding shield door. The outlet valve 91 is brought to its closed
position to prevent the flow of the liquid shielding material from
the multi-cell compartments of the core 73 of the door to the
outlet hose 75. The metallic channel 79 is screwed on to the
concrete wall 65 at the bottom of the wall opening. The guide 80
and the rollers 92 aid in the sliding of the door on the metallic
channel 79. The first second and the third cells 86, 87, 88 in the
core of the door are filled with the liquid shielding material 93.
When the sliding bottom outlet valve 91 is slid to the right, the
valve is brought in open position and the shielding liquid material
flows from the cells to the drainage tank 78 (FIG. 19) through the
outlet hose 75. The valve is brought to the left to stop the
drainage of the liquid from the cells by closing the outlets.
FIG. 23 demonstrates the sectional view of a single cell sliding
shield door's top inlet and its sliding mechanism. Except for the
single cell arrangement of the sliding shield door's core 73, the
rest of the door, its inlet and outlet valve's operation and its
sliding mechanism are similar to the top sectional view of the
multi-cell sliding hollow shield door as illustrated in FIG. 21. In
this case, only one cell needs to be filled by the inlet valve 94
with the liquid shielding material. Multiple single cell hollow
core doors are connected individually to the reserve tank 76. The
tank 76 is attached to individual metal channel 79 with guide 80
and the rollers 92. The single cell's drainage mechanism is similar
to the multi-cell door's drainage system but with minor
modifications. As shown in FIG. 24, each of the cells outlet hose
75 is connected to the drain tank 78.
FIG. 24 shows the sectional view of a single cell sliding shield
door's bottom outlet and its sliding mechanism. Except for the
single cell arrangement of the sliding shield door's core 73, the
rest of the door, its outlet valve's operation and its sliding
mechanism are similar to the bottom sectional view of the
multi-cell sliding hollow shield door as illustrated in FIG. 22. In
this case, only one cell needs to be emptied from the liquid
shielding material by the outlet valve 91. Multiple single cell
hollow core door are connected individually to the draining tank 78
by each door's drainage hose 75. As in FIG. 22, each single door's
bottom section is attached to individual metal channel 79 for
sliding of the door with guide 80 and rollers 92. The single cell
arrangement gives the flexibility to distribute the weight of the
liquid shielding material to multiple individual sliding hollow
core doors. Each of these doors are brought in front of the wall
opening 5 for its closure and moved away for its opening.
FIG. 25A and FIG. 25B demonstrate a different wall opening and
closing mechanism than the previous ones. In this case, a rotating
cylindrical solid shielding door 95 with a central opening 96 is
inserted at the site of the wall opening 5. This cylindrical shield
made of steel hollow core and filled with lead is made to rotate
with the aid of motor driven chain mechanisms 97 which are attached
to the top and bottom of this cylinder. This drive mechanism is
inserted into the concrete wall which at the site of the wall
opening 5 is modified at 98 for the accommodation of the
cylindrical shield. The deficient thickness created in the concrete
wall by attaching this drive mechanism is compensated with lead
sheets. Also provision is made for the mechanical rotation of the
cylinder in case of emergency with a retractable handle 99. In FIG.
25A, the wall opening 5 is brought to open position 100 by rotating
the cylindrical shield to bring its opening to face the CT room on
one side and the accelerator room at the other side. In FIG. 25B,
the rotating cylindrical shield door 95 is shown in its closed
position 101. The opening in the cylindrical shield door 96 is
brought to horizontal to the concrete wall 65 so that this opening
96 now face the concrete wall 65 at both ends and the solid
portions of this rotating cylindrical shield door faces the CT and
the accelerator rooms and shields the both rooms from radiation. As
described above, the safety of this cylindrical shield's operation
during the opening and closing of the wall opening 5 is assured by
safety interlocks. The accelerator's interlock for the door is
connected to this cylindrical door. The accelerator will be
activated only if the wall opening is closed completely and the
cylindrical door is at a predetermined position to assure the
required full thickness shielding of the wall opening is brought
into position.
FIG. 26 is a view of the sliding shield door from the accelerator
side of the wall opening and from the side of the diagnostic room.
The wall opening 5 is shown in its opened position. In FIG. 26A, at
the accelerator side, the configuration the sliding shield doors
are as described above with reference to FIG. 16. Multiple slabs of
shielding materials 9c are shown. In FIG. 26B, at the diagnostic
imaging side of the wall opening, the opening and closing mechanism
is as on the accelerator side except for the single slab sliding
shield door 9d.
FIG. 27A is a view of the accelerator side's sliding hollow core
door with the filling and draining of the liquid shielding material
as was described with reference to FIG. 19. The opposite side of
the wall opening 5 at the the diagnostic imagining device side, see
FIG. 27B, is fitted with a single slab sliding shield door 9d as
shown also in FIG. 26.
FIG. 28 illustrates a different configuration of the accelerator
room with mazes to reduce the shielding at the wall opening. In
this instance, the secondary barrier wall 102 in front of the
accelerator table is interposed in between a shorter maze wall 103
and a longer maze wall 104. The longer maze wall 104 with the
opening 105 for the door 106 and the shorter maze wall 103
circumvents the maze wall 102. The maze wall 102 has an opening 107
with a door 108. This opening 108 is at 0 degrees to the
accelerator table. The double doors 108, 105 facing the opening
107, and the distance from the accelerator to the ante-room's wall
110 assure only a much decreased energy scattered radiation
reaching these openings in the shared walls of the diagnostic room
and the accelerator's ante-room. The openings in the concrete wall
for patient transport from the diagnostic table are placed away
from the direct path of radiation from the accelerator. By this
arrangement only multiply scattered radiation with much reduced
energy will reach the wall openings 111. In general, the
construction of an accelerator room is done with maze walls to
reduce the shielding requirement for door. With maze walls, the
shielding for the door of a medical accelerator room is reduced to
about less than 6 mm of lead for most facilities. The same
principle of multiply scattered radiation with much reduced energy
reaching the wall openings 111 for the connection of the
accelerator room with the diagnostic room is applied here. Because
of this reduced shielding requirement, the doors 112 at these wall
openings 111 are treated the same as in the design of door for a
medical accelerator. Such construction will also allow to make
reduced thickness sliding shield door as was previously described
in FIG. 16 and 19, however, the patient transport through a door
opening is far more convenient than through the smaller wall
opening 5. From the diagnostic table 8, the patient is transferred
to a modified extension table 113 with rollers and is rolled on the
tracks 114 leading to the accelerator. The back side of the
diagnostic device's gantry's opening 59 faces the ante-room's wall
opening 111 and its door 112. This allows the routine imaging of a
patient with a device like the CT and the subsequent patient
transport to the accelerator room. For imaging of the head and neck
region, a head holder 51 (FIGS. 9A-C, 10A-C) is attached to the
present CT. Through the rearward exit 59 of the gantry of the
diagnostic device (FIG. 12) the patient is transported to the
extension table and then to the accelerator table. The top section
of this extension table 113 can be rotated to 360 degree to allow
the patient's transport from any of the wall opening conveniently.
This allows the patient to be placed on accelerator table with the
head closer to the accelerator's gantry, which is the common
treatment position of a patient on the accelerator table. Through
the guide rails 113 the extension table with the patient is brought
to the accelerator room. The accelerator 1 with its table 2 as
retracted towards its gantry 57 to make room for attachment of the
extension table is shown in the accelerator room 3. The flat table
top insert 17 (FIG. 3) with the patient is rolled over to the
accelerator table by rolling its rollers 24 on the grooves 31 of
the accelerator table(FIG. 9,10 and 13). Only one patient at a time
is brought to the accelerator's ante-room space 109. When the
accelerator is idle, a patient whose setup and verification is
completed is brought to the accelerator through the ante-room space
109. The extension table is connected to the accelerator table as
described in FIG.7 before the patient's transfer to the accelerator
table. The diagnostic rooms 6 with the table 8 and the gantry 18
are oriented towards the accelerator room at an angle to facilitate
the transport of the extension table on the tracks attached on the
floor at relatively straight paths. The diagnostic device's control
room 115 and the utility room 116 are also shown in this
figure.
In addition, an additional room 117 for special procedures such as
surgery 118 is attached to the anteroom of the accelerator room
through the door 119. Its door 120 opens to a diagnostic room while
door 121 is for entry and exit from outside. This unique
arrangement would greatly enhance both the quality and cost
efficiency of the surgery combined 3-D conformal radiation therapy.
The needed special surgical procedures can be done within the close
proximity of a diagnostic device such as a CT or an MRI. At
present, often surgery is done at a room far away from the
diagnostic CT or MRI with the attempted correlation with the images
previously obtained and subsequent transport of the patient to an
accelerator from this distant operating room for the intraoperative
3-D conformal radiation therapy. The advantages associated with the
availability of a surgical suite in association with a CT or MRI
unit and the accelerator for improved quality and cost efficiency
is obvious. It also facilitates the delivery of the brachytherapy
combined surgery and 3-D external radiation therapy with greater
precision due to the same advantages as the precise and online
target treatment volume definition at surgery in a surgical suite
in close proximity of an accelerator combined with a diagnostic
device.
FIG. 29 is another illustration of a different configuration of the
accelerator room with mazes to reduce the shielding at the wall
openings 105, for entry to the accelerator room from the ante-room
space 109 and the wall openings 111 at the shared wall of the
diagnostic room and the ante-room. In this instance, the opening
107 in the secondary barrier 102 is eliminated. This further
reduces the energy of the scattered radiation reaching the door 106
and the ante-room space's doors 112 and thus reduces the required
shielding for these doors. It also allows one to construct the
ante-room 109 with shielding equivalent to an x-ray room when the
diagnostic device used in the adjacent diagnostic room is an x-ray
generating unit such as a CT. The patient is transported from the
diagnostic table 8 to the ante-room 109 through the door opening
112. From the diagnostic table 8, the patient is transferred to the
modified extension table 113, as in FIG. 28, and is rolled on
tracks 114 to the accelerator room. Track 114 begins at the
diagnostic room and passes through the wall opening 111 to the
ante-room 109 and enters the accelerator room with bending 122 to
circumvent the barrier made by the maze wall 102. Except for these
modifications, the structural and functional features as well as
the identifying numerals shown in FIG. 29 are nearly identical to
those in FIG. 28.
In FIG. 30, a modified version of the single accelerator 1 combined
with multiple diagnostic devices 7 is shown. In this case, the
configuration in FIG. 15 is modified with maze walls that surrounds
the accelerator. The secondary barrier 123 in front of the
accelerator table has an opening 124 for entrance and exit to the
accelerator room 3 through this accelerator's anteroom 125. To
reduce the weight of the door 126 at the opening 124 in front of
the accelerator table, the door is made with less shielding
material but the radiation that leaks through this door is absorbed
by the ante-room's walls. The two sidewall doors 127 to the
anteroom 125 allow entrance and exit to the anteroom. At these
doors only, multiply scattered low energy radiation will reach and
hence only much less shielding is required. A semi-circular curved
track 128 on the floor surrounds the accelerator room. It connects
with each of the diagnostic rooms 6 that surround the accelerator
and passes through the anteroom 125. The diagnostic rooms 6 are
arranged to form a hexagonal about the accelerator room. The track
128 runs through the floor in between the accelerator room and the
diagnostic room. It is also connected to the accelerator room as it
enters the accelerator room's floor through the secondary barrier's
opening 124. A perpendicular track on the floor 129 runs from the
anteroom to the accelerator room and ends in front of the
accelerator table 2. It thus connects the semi-circular track 125
with the accelerator room. The extension table 113 is used to
transport patients from the diagnostic tables 8 to the accelerator
table 2. The diagnostic room's back exit door 130 opens to the
secondary space 131 in between the diagnostic room and the
accelerator room in the hexagonal arrangement of the diagnostic
room around the accelerator. The initial patient setup and
verification is done with the diagnostic device and subsequently,
the diagnostic table 8 is extended to the secondary space 131
through the accelerator gantry's back exit 59 and the diagnostic
room's back exit door 130. The extension table is rolled on the
semi-circular rails 128 on the floor to bring it near to the
diagnostic room's back exit door 130. The extension table's
rotating table top section is rotated to the diagnostic table and
both tables are connected together and the patient is transferred
to the extension table. After disconnecting the tables, the
extension table's top section is rotated to bring it back in
parallel to the rails on the floor 128 and the extension table is
rolled to the ante-room and then to the accelerator room on
connecting rails 129. The patient is transferred to the accelerator
table 2 by rolling the flat table top insert with the patient on
the grooves 31 of the accelerator table's cradle (FIG. 11). In
principle, the patient's transfer from the diagnostic table to the
accelerator table is the same as described under FIGS. 7, 9, 10,
13, 28 and 29, but with the necessary adaptation for a given
configuration of the room's layout. The entry and exit to the
secondary room 131, in between the accelerator and its anteroom and
the diagnostic room, is through the two doors 132 at both ends of
the hexagonal layout of this configuration. The diagnostic rooms
are equipped with entrance and exit doors 10. The accelerator
room's greater thickness concrete wall 11 and the diagnostic rooms
lesser thickness wall 12 are also shown in this illustrations.
FIG. 31 shows two accelerators with multiple diagnostic devices.
The accelerator 1 is equipped with a special purpose collimator 62
for special procedures such as the radiosurgery and is configured
at one end of the ante-room 109 and closer to the surgical room
117. The other megavoltage radiation therapy machine 123 is placed
at the other end of the ante-room 109 and is a conventional
accelerator for conventional megavoltage radiation therapy. The
rest of the illustration identifying the parts of the diagnostic
imaging device, the surgical room, the tracks, the extension table,
the wall and door openings, and the maze wall arrangements are as
described with respect to FIG. 28.
From the above descriptions, one skilled in the art would recognize
the advantages of this invention including:
After the desired patient setup is done with the CT, the CT-table
with the patient is moved towards an opening in the shared wall of
the accelerator and the CT room. The accelerator table is also
moved towards this common opening in the wall and the both tables
are latched together. The patient is then brought to the
accelerator table by moving the CT cradle towards the accelerator
table. The patient is then transferred to the accelerator table
without any changes in the patient's setup. Once the patient is
moved to the accelerator table, the CT-cradle is retracted and the
wall opening is closed with a protective shield for radiation
protection. The CT-table is then aligned with the accelerator's
treatment head and the radiation treatment is given to the desired
anatomic region of the patient. After the treatment is completed,
the patient leaves the accelerator room through its exit door and
the next patient whose setup is completed in the next adjacent CT
room is brought into the accelerator room and treated.
The disadvantage of the openings in the secondary barrier wall is
that it will need doors with heavy shielding material. The required
secondary barrier for the leakage radiation far exceeds the
required secondary barrier for the scattered radiation in the
megavoltage range. Unless a maze wall arrangement is made to
prevent the direct incidence of radiation at the shield door, this
door may weigh about 750 kg for a 6 MV accelerator beam. This heavy
weight of the door is an inconvenience. In this case, the weight of
the shielding door is distributed to multiple sliding doors. The
sliding shield door is like the beam shield attached to an
accelerator. Provisions for manual operation of these doors are
also made. The arrangement without the maze walls has the advantage
of easier patient transportation than the arrangement with the maze
walls in between the secondary barrier.
With the maze walled accelerator room, the door openings are
exposed only to the multiply scattered radiation of much reduced
energy. Like the door shielding of an accelerator room, with maze
walls interposed between the secondary barrier walls, the required
shielding at the door openings for a usual accelerator room is
reduced to about 6 mm thick lead. This allows larger wall opening
to be made with reduced shielding for the door making the patient
transport through the door easier. To take advantage of the reduced
shielding requirement at the door openings when maze walled
accelerator room construction is elected, this invention also
includes construction of the accelerator room with maze walls. It
also includes an anteroom to the accelerator room with required
shielding. In this instance, the patient is first transferred from
the diagnostic room to an ante-room to the accelerator through the
shared doors between the diagnostic room and the ante-room and then
to the accelerator room on extension table on rails. Whichever of
these systems is elected is based upon the specific needs and the
economical and the structural considerations of a specific
treatment facility.
After checking for the satisfactory positioning of the patient on
the accelerator table, the technical personal exits the room and
the doors are closed. The shield door's interlock with the
accelerator console assures the double check for the proper closure
of the shield doors. If any of the doors are opened or improperly
closed, the accelerator will not operate. Close circuit TVs
monitors the patients and the inside of the accelerator room. A
microphone and speakers at the control console maintain
communication with the patient when the doors are closed. These
precautions are the routine common practice in radiation therapy of
patients and the commercial accelerators are equipped with such
interlocks.
This configuration of multiple CT with one accelerator allows the
rapid turnover of patients in the accelerator room. The time taken
to deliver the usual about 200 cGy for daily treatment by the
accelerator is typically less than a minute. The total time taken
for the transport of the patient from the diagnostic table to the
accelerator table, closure of the wall opening and the automatic
accelerator's treatment setup as per each patient's initial plan
and completion of radiation takes much less time than when the
patient setup and treatment is done with the accelerator alone. For
conventional radiation therapy, the former may take about less than
5 minutes while the latter may take at least about 20 to 25 minutes
on the average. If the verification port films are also to be taken
with the accelerator, the time taken by the accelerator to complete
a patient's setup and treatment can almost double the routine daily
treatment. During 3D conformal radiation therapy like the
radiosurgery for intra-cranial lesion the average time taken is
much longer. Therefore at present only about four patients are
treated by stereotactic radiosurgery for intra-cranial lesions per
week. Because of the reduced time taken for a patient's treatment
at the accelerator, about for to five time more patients can be
treated with a single accelerator, enhancing the cost-efficiency of
this system. At present, a diagnostic device like a CT scan is much
cheaper than the accelerator and hence addition of multiple
diagnostic devices like the CT scans would not increase the overall
cost of this system.
In this invention, the daily patient setup is verified by the CT
with much superior anatomical delineation of the tumor site and its
surrounding normal tissue before each day's treatment. The present
existing methods of radiation therapy with accelerator do not have
this capability. The changes in the body contour due to loss of
weight swellings or other reasons, the changes in the tumor volume
under treatment and its changing anatomical relation to its
surrounding normal structures and the accurate estimation of the
geometric outline of tissue inhomogeneities of the treatment
regions are all estimated with the daily setup CT image. This CT
image is used for the daily on-line CT integrated dosimetric
calculations with a treatment planning computer. It is displayed on
a TV monitor as superimposed on the daily setup CT image. A
commercially available treatment planning computer is integrated
with the CT combined accelerator system for the daily treatment
verification. For the daily treatment setup and verification, only
orientation one or two CT slices may be needed and hence patients
are not kept long on the CT table. This greatly improves the
overall quality of the daily dosimetric calculations and the
quality of daily treatment. It also adds to the ease with which the
daily treatment setup is done and the treatment port with
superimposed dosimetry is verified. Such on-line quality control
checkup before each day's treatment is presently not available and
is not feasible.
The CT combined accelerator as in this invention, also improves the
quality and the cost efficiency of conformal radiation therapy. It
improves the patient setup and field verification, eliminates the
waiting time for access to an accelerator and the dead time for CT
data transfer from the Radiology department to the Radiation
Oncology department for treatment planning. The technical
improvements of this invention facilitates the stereotactic
radiation therapy of many patients a day than the present four
patients a week. It also improves the quality of this treatment
significantly. The improvement of the quality of this treatment is
much more important than the cost savings; but through the
significant cost savings of this invention, very many patients can
benefit from this advanced form of radiation therapy.
In brief, this invention's capabilities allow the improved quality
and highly cost effective radiation therapy for cancer as the
following. The patient is brought to the CT room and is placed on
the CT table in the desired treatment position. When needed, the
patient position is further secured with patient immobilization
devices. Port verification limited CT are taken for comparison with
the initial setup and the treatment plan. With the aid of a
treatment planning computer, the initial setup treatment plan is
superimposed on this CT for comparison. This enables the daily
on-line verification of the setup and dose distribution of the
intended treatment. After making the necessary adjustments in the
setup if necessary, the motor driven CT table with the patient on
it is advanced towards the opening in the wall or to the
accelerator's ante-room. When the patient is transported through
the wall opening, the accelerator table from the adjacent
accelerator room is also brought to the opening in the wall. The
tables are connected and fastened together. Through the track on
the table tops, the patient is moved from one table top to the
other and thus brought from the CT room to the accelerator room.
After closing the wall opening with the sliding shield door, the CT
room and the accelerator rooms are separated and functions
independently of each other. The patient on the accelerator table
is placed under the accelerator's treatment head and the treatment
to the desired anatomical site as was setup and verified with the
CT is given. In the alternative arrangement with an ante-room to
the accelerator, after the patient setup and verification in the CT
room is completed, the patient is transferred from the CT table to
an intermediate accelerator table and which is then rolled on
tracks attached on the floor of the ante-room and leads to the
accelerator room. The patient is then transferred to the
accelerator table. After completion of the treatment, patient
leaves the accelerator room through its door. In the CT room, a new
patient setup will begin. The time taken to complete the radiation
with the accelerator is much shorter than the patient setup and
verification with the CT. This difference in time taken for setup
and verification by the CT and the actual treatment by the
accelerator allows treatment of several patients with one
accelerator within the time period of a single patient setup and
verification by the CT. This allows another patient to be brought
into the accelerator room whose setup and verification has
completed with an other adjacent CT. This follows another patients
radiation treatment whose setup and verification is completed in an
other CT room. Whenever the accelerator room and the CT rooms
function independently, all the connecting wall openings and doors
are closed. In this manner, a single accelerator can treat very
many patients with much higher accuracy than when the patient
setup, verification and the treatment all are done with the
accelerator. It also reduces the turn-around time for 3D conformal
radiation therapy and stereotactic radiosurgery while improving the
quality of this treatments further as described earlier. When the
diagnostic device is not in use with the accelerator, it is used as
a stand alone imaging device of a diagnostic Radiology Department.
All these combined advantages of this invention provides a great
deal of cost savings in the radiation therapy of cancer while the
quality of this cancer treatment is many fold improved.
The disclosure of the invention described herein above represents
the preferred embodiments of the invention; however, variation
thereof, in the form, construction and arrangement of the
accelerator and the CT thereof and modified application of the
invention are possible without departing from the spirit and scope
of the appended claims.
* * * * *